Chapter VIII: Part 8

COLE, TIMOTHY (1852- ), American wood engraver, was born in London, England, in 1852, his family emigrating to the United States in 1858. He established himself in Chicago, where in the great fire of 1871 he lost everything he possessed. In 1875 he removed to New York, finding work on the _Century_ (then _Scribner's_) magazine. He immediately attracted attention by his unusual facility and his sympathetic interpretation of illustrations and pictures, and his publishers sent him abroad in 1883 to engrave a set of blocks after the old masters in the European galleries. These achieved for him a brilliant success. His reproductions of Italian, Dutch, Flemish and English pictures were published in book form with appreciative notes by the engraver himself. Though the advent of new mechanical processes had rendered wood engraving almost a lost art and left practically no demand for the work of such craftsmen, Mr Cole was thus enabled to continue his work, and became one of the foremost contemporary masters of wood engraving. He received a medal of the first class at the Paris Exhibition of 1900, and the only grand prize given for wood engraving at the Louisiana Purchase Exposition at St Louis, Missouri, in 1904.

COLE, VICAT (1833-1893), English painter, born at Portsmouth on the 17th of April 1833, was the son of the landscape painter, George Cole, and in his practice followed his father's lead with marked success. He exhibited at the British Institution at the age of nineteen, and was first represented at the Royal Academy in 1853. His election as an associate of this institution took place in 1870, and he became an Academician ten years later. He died in London on the 6th of April 1893. The wide popularity of his work was due partly to the simple directness of his technical method, and partly to his habitual choice of attractive material. Most of his subjects were found in the counties of Surrey and Sussex, and along the banks of the Thames. One of his largest pictures, "The Pool of London," was bought by the Chantrey Fund Trustees in 1888, and is now in the Tate Gallery.

See Robert Chignell, _The Life and Paintings of Vicat Cole, R.A._
(London, 1899).

COLEBROOKE, HENRY THOMAS (1765-1837), English Orientalist, the third son of Sir George Colebrooke, 2nd baronet, was born in London on the 15th of June 1765. He was educated at home; and when only fifteen he had made considerable attainments in classics and mathematics. From the age of twelve to sixteen he resided in France, and in 1782 was appointed to a writership in India. About a year after his arrival there he was placed in the board of accounts in Calcutta; and three years later he was removed to a situation in the revenue department at Tirhut. In 1789 he was removed to Purneah, where he investigated the resources of that part of the country, and published his _Remarks on the Husbandry and Commerce of Bengal_, privately printed in 1795, in which he advocated free trade between Great Britain and India. After eleven years' residence in India, Colebrooke began the study of Sanskrit; and to him was confided the translation of the great _Digest of Hindu Laws_, which had been left unfinished by Sir William Jones. He translated the two treatises _Mitacshara_ and _Dayabhaga_ under the title _Law of Inheritance_. He was sent to Nagpur in 1799 on a special mission, and on his return was made a judge of the new court of appeal, over which he afterwards presided. In 1805 Lord Wellesley appointed him professor of Hindu Law and Sanskrit at the college of Fort William. During his residence at Calcutta he wrote his _Sanskrit Grammar_ (1805), some papers on the religious ceremonies of the Hindus, and his _Essay on the Vedas_ (1805), for a long time the standard work on the subject. He became member of council in 1807 and returned to England seven years later. He died on the 18th of March 1837. He was a director of the Asiatic Society, and many of the most valuable papers in the society's _Transactions_ were communicated by him.

His life was written by his son, Sir T. E. Colebrooke, in 1873.

COLEMANITE, a hydrous calcium borate, Ca2B6O11 + 5H2O, found in California as brilliant monoclinic crystals. It contains 50.9% of boron trioxide, and is an important source of commercial borates and boracic acid. Beautifully developed crystals, up to 2 or 3 in. in length, encrust cavities in compact, white colemanite; they are colourless and transparent, and the brilliant lustre of their faces is vitreous to adamantine in character. There is a perfect cleavage parallel to the plane of symmetry of the crystals. Hardness 4-4-1/2; specific gravity 2.42. The mineral was first discovered in 1882 in Death Valley, Inyo county, California, and in the following year it was found in greater abundance near Daggett in San Bernardino county, forming with other borates and borosilicates a bed in sedimentary strata of sandstones and clays; in more recent years very large masses have been found and worked in these localities, and also in Los Angeles county (see Special Report, 1905, of U.S. Census Bureau on _Mines and Quarries_; and _Mineral Resources of the U.S._, 1907).

Priceite and pandermite are hydrous calcium borates with very nearly the same composition as colemanite, and they may really be only impure forms of this species. They are massive white minerals, the former friable and chalk-like, and the latter firm and compact in texture. Priceite occurs near Chetco in Curry county, Oregon, where it forms layers between a bed of slate and one of tough blue steatite; embedded in the steatite are rounded masses of priceite varying in size from that of a pea to masses weighing 200 lb. Pandermite comes from Asia Minor, and is shipped from the port of Panderma on the Sea of Marmora: it occurs as large nodules, up to a ton in weight, beneath a thick bed of gypsum.

Another borate of commercial importance found abundantly in the Californian deposits is ulexite, also known as boronatrocalcite or "cotton-ball," a hydrous calcium and sodium borate, CaNaB5O9 + 8H2O, which forms rounded masses consisting of a loose aggregate of fine fibres. It is the principal species in the borate deposits in the Atacama region of South America. (L. J. S.)

COLENSO, JOHN WILLIAM (1814-1883), English bishop of Natal, was born at St Austell, Cornwall, on the 24th of January 1814. His family were in embarrassed circumstances, and he was indebted to relatives for the means of university education. In 1836 he was second wrangler and Smith's prizeman at Cambridge, and in 1837 he became fellow of St John's. Two years later he went to Harrow as mathematical tutor, but the step proved an unfortunate one. The school was just then at the lowest ebb, and Colenso not only had few pupils, but lost most of his property by a fire. He went back to Cambridge, and in a short time paid off heavy debts by diligent tutoring and the proceeds of his series of manuals of algebra (1841) and arithmetic (1843), which were adopted all over England. In 1846 he became rector of Forncett St Mary, Norfolk, and in 1853 he was appointed bishop of Natal. He at once devoted himself to acquiring the Zulu language, of which he compiled a grammar and a dictionary, and into which he translated the New Testament and other portions of Scripture. He had already given evidence, in a volume of sermons dedicated to Maurice, that he was not satisfied with the traditional views about the Bible. The puzzling questions put to him by the Zulus strengthened him in this attitude and led him to make a critical examination of the Pentateuch. His conclusions, positive and negative, were published in a series of treatises on the Pentateuch, extending from 1862 to 1879, and, being in advance of his time, were naturally disputed in England with a fervour of conviction equal to his own. On the continent they attracted the notice of Abraham Kuenen, and furthered that scholar's investigations.

While the controversy raged in England, the South African bishops, whose suspicions Colenso had already incurred by the liberality of his views respecting polygamy among native converts and by a commentary upon the Epistle to the Romans (1861), in which he combated the doctrine of eternal punishment, met in conclave to condemn him, and pronounced his deposition (December 1863). Colenso, who had refused to appear before their tribunal otherwise than as sending a protest by proxy, appealed to the privy council, which pronounced that the metropolitan of Cape Town (Robert Gray) had no coercive jurisdiction and no authority to interfere with the bishop of Natal. No decision, therefore, was given upon the merits of the case. His adversaries, though unable to obtain his condemnation, succeeded in causing him to be generally inhibited from preaching in England, and Bishop Gray not only excommunicated him but consecrated a rival bishop for Natal (W. K. Macrorie), who, however, took his title from Maritzburg. The contributions of the missionary societies were withdrawn, but an attempt to deprive him of his episcopal income was frustrated by a decision of the courts. Colenso, encouraged by a handsome testimonial raised in England, to which many clergymen subscribed, returned to his diocese, and devoted the latter years of his life to further labours as a biblical commentator and translator. He also championed the cause of the natives against Boer oppression and official encroachments, a course by which he made more enemies among the colonists than he had ever made among the clergy. He died at Durban on the 20th of June 1883. His daughter Frances Ellen Colenso (1840-1887) published two books on the relations of the Zulus to the British (1880 and 1885), taking a pro-Zulu view; and an elder daughter, Harriette E. Colenso (b. 1847), became prominent as an advocate of the natives in opposition to their treatment by Natal, especially in the case of Dinizulu in 1888-1889 and in 1908-1909.

See his _Life_ by Sir G. W. Cox (2 vols., London, 1888).

COLENSO, a village of Natal on the right or south bank of the Tugela river, 16 m. by rail south by east of Ladysmith. It was the scene of an action fought on the 15th of December 1899 between the British forces under Sir Redvers Buller and the Boers, in which the former were repulsed. (See LADYSMITH.)

COLEOPTERA, a term used in zoological classification for the true beetles which form one of the best-marked and most natural of the orders into which the class Hexapoda (or Insecta) has been divided. For the relationship of the Coleoptera to other orders of insects see HEXAPODA. The name (Gr. [Greek: koleos], a sheath, and [Greek: ptera], wings) was first used by Aristotle, who noticed the firm protective sheaths, serving as coverings for the hind-wings which alone are used for flight, without recognizing their correspondence with the fore-wings of other insects.

These firm fore-wings, or elytra (fig. 1, A), are usually convex above, with straight hind margins (_dorsa_); when the elytra are closed, the two hind margins come together along the mid-dorsal line of the body, forming a _suture_. In many beetles the hind-wings are reduced to mere vestiges useless for flight, or are altogether absent, and in such cases the two elytra are often fused together at the suture; thus organs originally intended for flight have been transformed into an armour-like covering for the beetle's hind-body. In correlation with their heavy build and the frequent loss of the power of flight, many beetles are terrestrial rather than aerial in habit, though a large proportion of the order can fly well.

Aristotle's term was adopted by Linnaeus (1758), and has been universally used by zoologists. The identification of the elytra of beetles with the fore-wings of other insects has indeed been questioned (1880) by F. Meinert, who endeavoured to compare them with the tegulae of Hymenoptera, but the older view was securely established by the demonstration in pupal elytra by J. G. Needham (1898) and W. L. Tower (1903), of nervures similar to those of the hind-wing, and by the proof that the small membranous structures present beneath the elytra of certain beetles, believed by Meinert to represent the whole of the true fore-wings, are in reality only the alulae.

_Structure._--Besides the conspicuous character of the elytra, beetles are distinguished by the adaptation of the jaws for biting, the mandibles (fig. 1, Bb) being powerful, and the first pair of maxillae (fig. 1, Bc) usually typical in form. The maxillae of the second pair (fig. 1, Bd) are very intimately fused together to form what is called the "lower lip" or labium, a firm transverse plate representing the fused basal portions of the maxillae, which may carry a small median "ligula," representing apparently the fused inner maxillary lobes, a pair of paraglossae (outer maxillary lobes), and a pair of palps. The feelers of beetles differ greatly in the different families (cf. figs. 2b, 9b and 26b, c); the number of segments is usually eleven, but may vary from two to more than twenty.

The head is extended from behind forwards, so that the crown (epicranium) is large, while the face (clypeus) is small. The chin (gula) is a very characteristic sclerite in beetles, absent only in a few families, such as the weevils. There is usually a distinct labrum (fig. 1, Ba).

The prothorax is large and "free," i.e. readily movable on the mesothorax, an arrangement usual among insects with the power of rapid running. The tergite of the prothorax (pronotum) is prominent in all beetles, reaching back to the bases of the elytra and forming a substantial shield for the front part of the body. The tergal regions of the mesothorax and of the metathorax are hidden under the pronotum and the elytra when the latter are closed, except that the mesothoracic scutellum is often visible--a small triangular or semicircular plate between the bases of the elytra (fig. 1, A). The ventral region of the thoracic skeleton is complex, each segment usually possessing a median sternum with paired episterna (in front) and epimera (behind). The articular surfaces of the haunches (coxae) of the fore-legs are often conical or globular, so that each limb works in a ball-and-socket joint, while the hind haunches are large, displacing the ventral sclerites of the first two abdominal segments (fig. 1, C). The legs themselves (fig. 1, A) are of the usual insectan type, but in many families one, two, or even three of the five foot-segments may be reduced or absent. In beetles of aquatic habit the intermediate and hind legs are modified as swimming-organs (fig. 2, a), while in many beetles that burrow into the earth or climb about on trees the fore-legs are broadened and strengthened for digging, or lengthened and modified for clinging to branches. The hard fore-wings (elytra) are strengthened with marginal ridges, usually inflected ventrally to form epipleura which fit accurately along the edges of the abdomen. The upper surface of the elytron is sharply folded inwards at intervals, so as to give rise to a regular series of external longitudinal furrows (striae) and to form a set of supports between the two chitinous layers forming the elytron. The upper surface often shows a number of impressed dots (punctures). Along the sutural border of the elytron, the chitinous lamella forms a tubular space within which are numerous glands. The glands occur in groups, and lead into common ducts which open in several series along the suture. Sometimes the glands are found beneath the disk of the elytron, opening by pores on the surface. The hind-wings, when developed, are characteristic in form, possessing a sub-costal nervure with which the reduced radial nervure usually becomes associated. There are several curved median and cubital nervures and a single anal, but few cross nervures or areolets. The wing, when not in use, is folded both lengthwise and transversely, and doubled up beneath the elytron; to permit the transverse folding, the longitudinal nervures are interrupted.

Ten segments can be recognized--according to the studies of K. W. Verhoeff (1804-1896)--in a beetle's abdomen, but the tenth sternite is usually absent. On account of the great extension of the metathorax and the haunches of the large hind-legs, the first abdominal sternite is wanting, and the second is usually so much reduced that the foremost apparent ventral sclerite of the abdomen represents the third sternite. From this point backwards the successive abdominal segments, as far as the seventh or eighth, can be readily made out. The ninth and tenth segments are at most times retracted within the eighth. The female can protrude a long flexible tube in connexion with the eighth segment, carrying the sclerites of the ninth at its extremity, and these sclerites may carry short hairy processes--the stylets. This flexible tube is the functional ovipositor, the typical insectan ovipositor with its three pairs of processes (see HEXAPODA) being undeveloped among the Coleoptera. In male beetles, however, the two pairs of genital processes (paramera) belonging to the ninth abdominal segment are always present, though sometimes reduced. Between them is situated, sometimes asymmetrically, the prominent intromittent organ.

In the structure of the digestive system, beetles resemble most other mandibulate insects, the food-canal consisting of gullet, crop, gizzard, mid-gut or stomach, intestine and rectum. The stomach is beset throughout its length with numerous small, finger-like caecal tubes. The excretory (malpighian) tubes are few in number, either four or six. Many beetles have, in connexion with the anus, glands which secrete a repellent acid fluid, serving as a defence for the insect when attacked. The "bombardier" ground beetles (fig. 5) have this habit. Oil-beetles (figs. 23 and 24) and ladybirds (fig. 32) defend themselves by ejecting drops of fluid from the knee-joints. The nervous system is remarkably concentrated in some beetles, the abdominal ganglia showing a tendency to become shifted forward and crowded together, and in certain chafers all the thoracic and abdominal ganglia are fused into a single nerve-centre situated in the thorax,--a degree of specialization only matched in the insectan class among the Hemiptera and some muscid flies.

_Development._--The embryonic development (see HEXAPODA) has been
carefully studied in several genera of beetles. As regards growth
after hatching, all beetles undergo a "complete" metamorphosis, the
wing-rudiments developing beneath the cuticle throughout the larval
stages, and a resting pupal stage intervening between the last larval
instar[1] and the imago. The coleopterous pupa (figs. 2d, 3c) is
always "free," the legs, wings and other appendages not being fixed
to the body as in the pupa of a moth, and the likeness of pupa to
perfect insect is very close.

The most striking feature in the development of beetles is the great
diversity noticeable in the outward form of the larva in different
families. The larva of a ground-beetle or a carnivorous water-beetle
(fig. 2 c) is an active elongate grub with well-armoured cuticle. The
head--carrying feelers, mandibles and two pairs of maxillae--is
succeeded by the three thoracic segments, each bearing a pair of
strong five-segmented legs, whose feet, like those of the adult, carry
two claws. Ten segments can be distinguished in the tapering abdomen,
the ninth frequently bearing a pair of tail-feelers (cerci), and the
tenth, attached ventrally to the ninth, having the anal opening at its
extremity and performing the function of a posterior limb, supporting
and temporarily fixing the tail end of the insect on the surface over
which it crawls. Such a typically "campodeiform" grub, moving actively
about in pursuit of prey, is the one extreme of larval structure to be
noticed among the Coleoptera. The other is exemplified by the white,
wrinkled, soft-skinned, legless grub of a weevil, which lives
underground feeding on roots, or burrows in the tissues of plants
(fig. 3 b). Between these two extremes we find various transitional
forms: an active larva, as described above, but with four-segmented,
single-clawed legs, as among the rove-beetles and their allies; the
body well armoured, but slender and worm-like, with very short legs as
in wireworms and mealworms (figs. 18, 21 b); the body shortened, with
the abdomen swollen, but protected with tubercles and spines, and with
longish legs adapted for an active life, as in the predaceous larvae
of ladybirds; the body soft-skinned, swollen and caterpillar-like,
with legs well developed, but leading a sluggish underground life, as
in the grub of a chafer; the body soft-skinned and whitish, and the
legs greatly reduced in size, as in the wood-feeding grub of a
longhorn beetle. In the case of certain beetles whose larvae do not
find themselves amid appropriate food from the moment of hatching, but
have to migrate in search of it, an early larval stage, with legs, is
followed by later sluggish stages in which legs have disappeared,
furnishing examples of what is called hypermetamorphosis. For example,
the grub of a pea or bean beetle (_Bruchus_) is hatched, from the egg
laid by its mother on the carpel of a leguminous flower, with three
pairs of legs and spiny processes on the prothorax. It bores through
and enters the developing seed, where it undergoes a moult and becomes
legless. Similarly the newly-hatched larva of an oil-beetle (_Meloe_)
is an active little campodeiform insect, which, hatched from an egg
laid among plants, waits to attach itself to a passing bee. Carried to
the bee's nest, it undergoes a moult, and becomes a fat-bodied grub,
ready to lead a quiet life feeding on the bee's rich food-stores.

FIG. 3.--Grain Weevils. a, _Calandra granaria_; b, larva; c, pupa; d, _C. oryzae_.]

_Distribution and Habits._--The Coleoptera are almost world-wide in their distribution, being represented in the Arctic regions and on almost all oceanic islands. Most of the dominant families--such as the _Carabidae_ (ground-beetles), _Scarabaeidae_ (chafers), or _Curculionidae_ (weevils) have a distribution as wide as the order. But while some large families, such as the _Staphylinidae_ (rove-beetles) are especially abundant on the great northern continents, becoming scarcer in the tropics, others, the _Cicindelidae_ (tiger-beetles), for example, are most strongly represented in the warmer regions of the earth, and become scarce as the collector journeys far to south or north. The distribution of many groups of beetles is restricted in correspondence with their habits; the _Cerambycidae_ (longhorns), whose larvae are wood-borers, are absent from timberless regions, and most abundant in the great tropical forests. Some families are very restricted in their range. The _Amphizoidae_, for example, a small family of aquatic beetles, are known only from western North America and Eastern Tibet, while an allied family, the _Pelobiidae_, inhabit the British Isles, the Mediterranean region, Tibet and Australia. The beetles of the British islands afford some very interesting examples of restricted distribution among species. For example, large and conspicuous European beetles, such as the stag-beetle (fig. 1, _Lucanus cervus_) and the great water-beetle (_Hydrophilus piceus_, fig. 20), are confined to eastern and southern Britain, and are unknown in Ireland. On the other hand, there are Arctic species like the ground-beetle, _Pelophila borealis_, and south-western species like the boring weevil, _Mesites Tardyi_, common in Ireland, and represented in northern or western Britain, but unknown in eastern Britain or in Central Europe. Careful study of insular faunas, such as that of Madeira by T. V. Wollaston, and of the Sandwich Islands by D. Sharp, and the comparison of the species found with those of the nearest continental land, furnish the student of geographical distribution with many valuable and suggestive facts.

Notes on habit are given below in the accounts of the various families. In general it may be stated that beetles live and feed in almost all the diverse ways possible for insects. There are carnivores, herbivores and scavengers among them. Various species among those that are predaceous attack smaller insects, hunt in packs crustaceans larger than themselves, insert their narrow heads into snail-shells to pick out and devour the occupants, or pursue slugs and earthworms underground. The vegetable-feeders attack leaves, herbaceous or woody stems and roots; frequently different parts of a plant are attacked in the two active stages of the life-history; the cockchafers, for example, eating leaves, and their grubs gnawing roots. Some of the scavengers, like the burying beetles, inter the bodies of small vertebrates to supply food for themselves and their larvae, or, like the "sacred" beetle of Egypt, collect for the same purpose stores of dung. Many beetles of different families have become the "unbidden guests" of civilized man, and may be found in dwelling-houses, stores and ships' cargoes, eating food-stuffs, paper, furniture, tobacco and drugs. Hence we find that beetles of some kind can hold their own anywhere on the earth's surface. Some climb trees and feed on leaves, while others tunnel between bark and wood. Some fly through the air, others burrow in the earth, while several families have become fully adapted to life in fresh water. A large number of beetles inhabit the deep limestone caves of Europe and North America, while many genera and some whole families are at home nowhere but in ants' nests. Most remarkable is the presence of a number of beetles along the seashore between tide-marks, where, sheltered in some secure nook, they undergo immersion twice daily, and have their active life confined to the few hours of the low ebb.

_Stridulating Organs._--Many beetles make a hissing or chirping sound by rubbing a "scraper," formed by a sharp edge or prominence on some part of their exoskeleton, over a "file" formed by a number of fine ridges situate on an adjacent region. These stridulating organs were mentioned by C. Darwin as probable examples of the action of sexual selection; they are, however, frequently present in both sexes, and in some families also in the larvae. An account of the principal types of stridulators that have been described has been published by C. J. Gahan (1900). The file may be on the head--either upper or lower surface--and the scraper formed by the front edge of the prothorax, as in various wood-boring beetles (_Anobium_ and _Scolytus_). Or ridged areas on the sides of the prothorax may be scraped by "files" on the front thighs, as in some ground-beetles. Among the longhorn beetles, the prothorax scrapes over a median file on the mid-dorsal aspect of the mesothorax. In a large number of beetles of different families, stridulating areas occur on various segments of the abdomen, and are scraped by the elytra. It is remarkable that these organs are found in similar positions in genera belonging to widely divergent families, while two genera of the same family may have them in different positions. It follows, therefore, that they have been independently acquired in the course of the evolution of the Coleoptera.

Stridulating organs among beetle-larvae have been noted, especially in the wood-feeding grub of the stag-beetles (_Lucanidae_) and their allies the _Passalidae_, and in the dung-eating grubs of the dor-beetles (_Geotrupes_), which belong to the chafer family (_Scarabaeidae_). These organs are described by J. C. Schiodte and D. Sharp; in the stag-beetle larva a series of short tubercles on the hind-leg is drawn across the serrate edge of a plate on the haunch of the intermediate legs, while in the Passalid grub the modified tip of the hind-leg acts as a scraper, being so shortened that it is useless for locomotion, but highly specialized for producing sound. Whatever may be the true explanation of stridulating organs in adult beetles, sexual selection can have had nothing to do with the presence of these highly-developed larval structures. It has been suggested that the power of stridulation would be advantageous to wood-boring grubs, the sound warning each of the position of its neighbour, so that adjacent burrowers may not get in each other's way. The root-feeding larvae of the cockchafer and allied members of the _Scarabaeidae_ have a ridged area on the mandible, which is scraped by teeth on the maxillae, apparently forming a stridulating organ.

_Luminous Organs._--The function of the stridulating organs just described is presumably to afford means of recognition by sound. Some beetles emit a bright light from a portion of their bodies, which leads to the recognition of mate or comrade by sight. In the wingless female glow-worm (_Lampyris_, fig. 15 f) the luminous region is at the hinder end, the organ emitting the light consisting, according to H. von Wielowiejski (1882), of cells similar to those of the fat-body, containing a substance that undergoes oxidation. The illumination is intermittent, and appears to be under the control of the insect's nervous system. The well-known "fire-flies" of the tropics are large click-beetles (_Elateridae_), that emit light from paired spots on the prothorax and from the base of the ventral abdominal region. The luminous organs of these beetles consist of a specialized part of the fat-body, with an inner opaque and an outer transparent layer. Its structure has been described by C. Heinemann, and its physiology by R. Dubois (1886), who considers that the luminosity is due to the influence of an enzyme in the cells of the organ upon a special substance in the blood. The eggs and larvae of the fire-flies are luminous as well as the perfect beetles.

_Fossil History._--The Coleoptera can be traced back farther in time than any other order of insects with complete transformations, if the structures that have been described from the Carboniferous rocks of Germany are really elytra. In the Triassic rocks of Switzerland remains of weevils (_Curculionidae_) occur, a family which is considered by many students the most specialized of the order. And when we know that the _Chrysomelidae_ and _Buprestidae_ also lived in Triassic, and the _Carabidae_, _Elateridae_, _Cerambycidae_ and _Scarabaeidae_, in Liassic times, we cannot doubt that the great majority of our existing families had already been differentiated at the beginning of the Mesozoic epoch. Coming to the Tertiary we find the Oligocene beds of Aix, of east Prussia (amber) and of Colorado, and the Miocene of Bavaria, especially rich in remains of beetles, most of which can be referred to existing genera.

_Classification._--The Coleoptera have been probably more assiduously studied by systematic naturalists than any other order of insects. The number of described species can now hardly be less than 100,000, but there is little agreement as to the main principles of a natural classification. About eighty-five families are generally recognized; the difficulty that confronts the zoologists is the arrangement of these families in "superfamilies" or "sub-orders." Such obvious features as the number of segments in the foot and the shape of the feeler were used by the early entomologists for distinguishing the great groups of beetles. The arrangement dependent on the number of tarsal segments--the order being divided into tribes _Pentamera_, _Tetramera_, _Heteromera_ and _Trimera_--was suggested by E. L. Geoffroy in 1762, adopted by P. A. Latreille, and used largely through the 19th century. W. S. Macleay's classification (1825), which rested principally on the characters of the larvae, is almost forgotten nowadays, but it is certain that in any systematic arrangement which claims to be natural the early stages in the life-history must receive due attention. In recent years classifications in part agreeing with the older schemes but largely original, in accord with researches on the comparative anatomy of the insects, have been put forward. Among the more conservative of these may be mentioned that of D. Sharp (1899), who divides the order into six great series of families: _Lamellicornia_ (including the chafers and stag-beetles and their allies with five-segmented feet and plate-like terminal segments to the feelers); _Adephaga_ (carnivorous, terrestrial and aquatic beetles, all with five foot-segments); _Polymorpha_ (including a heterogeneous assembly of families that cannot be fitted into any of the other groups); _Heteromera_ (beetles with the fore and intermediate feet five-segmented, and the hind-feet four-segmented); _Phytophaga_ (including the leaf-beetles, and longhorns, distinguished by the apparently four-segmented feet), and _Rhynchophora_ (the weevils and their allies, with head prolonged into a snout, and feet with four segments). L. Ganglbauer (1892) divides the whole order into two sub-orders only, the _Caraboidea_ (the _Adephaga_ of Sharp and the older writers) and the _Cantharidoidea_ (including all other beetles), since the larvae of _Caraboidea_ have five-segmented, two-clawed legs, while those of all other beetles have legs with four segments and a single claw. A. Lameere (1900) has suggested three sub-orders, the _Cantharidiformia_ (including the _Phytophaga_, the _Heteromera_, the _Rhynchophora_ and most of the _Polymorpha_ of Sharp's classification), the _Staphyliniformia_ (including the rove-beetles, carrion-beetles and a few allied families of Sharp's _Polymorpha_), and the _Carabidiformia_ (_Adephaga_). Lameere's classification is founded on the number of abdominal sterna, the nervuration of the wings, the number of malpighian tubules (whether four or six) and other structural characters. Preferable to Lameere's system, because founded on a wider range of adult characters and taking the larval stages into account, is that of H. J. Kolbe (1901), who recognizes three sub-orders: (i.) the _Adephaga_; (ii.) the _Heterophaga_, including the _Staphylinoidea_, the _Actinorhabda_ (_Lamellicornia_), the _Heterorhabda_ (most of Sharp's _Polymorpha_), and the _Anchistopoda_ (the _Phytophaga_, with the ladybirds and some allied families which Sharp places among the _Polymorpha_); (iii.) the _Rhynchophora_.

Students of the Coleoptera have failed to agree not only on a system of classification, but on the relative specialization of some of the groups which they all recognize as natural. Lameere, for example, considers some of his _Cantharidiformia_ as the most primitive Coleoptera. J. L. Leconte and G. H. Horn placed the _Rhynchophora_ (weevils) in a group distinct from all other beetles, on account of their supposed primitive nature. Kolbe, on the other hand, insists that the weevils are the most modified of all beetles, being highly specialized as regards their adult structure, and developing from legless maggots exceedingly different from the adult; he regards the Adephaga, with their active armoured larvae with two foot-claws, as the most primitive group of beetles, and there can be little doubt that the likeness between larvae and adult may safely be accepted as a primitive character among insects. In the Coleoptera we have to do with an ancient yet dominant order, in which there is hardly a family that does not show specialization in some point of structure or life-history. Hence it is impossible to form a satisfactory linear series.

In the classification adopted in this article, the attempt has been made to combine the best points in old and recent schemes, and to avoid the inconvenience of a large heterogeneous group including the vast majority of the families.

ADEPHAGA.--This tribe includes beetles of carnivorous habit with five
segments on every foot, simple thread-like feelers with none of the
segments enlarged to form club or pectination, and the outer lobs
(galea) of the first maxilla usually two-segmented and palpiform (fig.
4 b). The transverse fold of the hind-wing is towards the tip, about
two-thirds of the wing-length from the base. At this fold the median
nervure stops and is joined by a cross nervure to the radial, which
can be distinguished throughout its length from the subcostal. There
are four malpighian tubules. In the ovarian tubes of Adephaga small
yolk-chambers alternate with the egg-chambers, while in all other
beetles there is only a single large yolk-chamber at the narrow end of
the tube. The larvae (fig. 2 c) are active, with well-chitinized
cuticle, often with elongate tail-feelers (cerci), and with
five-segmented legs, the foot-segment carrying two claws.

The generalized arrangement of the wing-nervure and the nature of the
larva, which is less unlike the adult than in other beetles,
distinguish this tribe as primitive, although the perfect insects are,
in the more dominant families, distinctly specialized. Two very small
families of aquatic beetles seem to stand at the base of the series,
the _Amphizoidae_, whose larvae are broad and well armoured with short
cerci, and the _Pelobiidae_, which have elongate larvae, tapering to
the tail end, where are long paired cerci and a median process,
recalling the grub of a Mayfly.

The _Dyticidae_ (fig. 2) are Adephaga highly specialized for life in
the water, the hind-legs having the segments short, broad and fringed,
so as to be well adapted for swimming, and the feet without claws. The
metasternum is without the transverse linear impression that is found
in most families of Adephaga. The beetles are ovoid in shape, with
smooth contours, and the elytra fit over the edges of the abdomen so
as to enclose a supply of air, available for use when the insect
remains under water. The fore-legs of many male dyticids have the
three proximal foot-segments broad and saucer-shaped, and covered
with suckers, by means of which they secure a firm hold of their
mates. Larval dyticids (fig. 2 b) possess slender, curved, hollow
mandibles, which are perforated at the tip and at the base, being thus
adapted for sucking the juices of victims. Large dyticid larvae often
attack small fishes and tadpoles. They breathe by piercing the surface
film with the tail, where a pair of spiracles are situated. The pupal
stage is passed in an earthen cell, just beneath the surface of the
ground. Nearly 2000 species of _Dyticidae_ are known: they are
universally distributed, but are most abundant in cool countries. The
_Haliplidae_ form a small aquatic family allied to the _Dyticidae_.

The _Carabidae_, or ground-beetles, comprising 13,000 species, form
the largest and most typical family of the Adephaga (figs. 4, 5, 6),
the legs of all three pairs being alike and adapted for rapid running.
In many _Carabidae_ the hind-wings are reduced or absent, and the
elytra fused together along the suture. Many of our native species
spend the day lurking beneath stones, and sally forth at night in
pursuit of their prey, which consists of small insects, earthworms and
snails. But a number of the more brightly coloured ground-beetles run
actively in the sunshine. The carabid larva is an active well-armoured
grub with the legs and cerci variable in length. Great differences in
the general form of the body may be observed in the family. For
example, the stout, heavy body of _Carabus_ (fig. 6) contrasts
markedly with the wonderful flattened abdomen and elytra of
_Mormolyce_ (fig. 4), a Malayan genus found beneath fallen trees, a
situation for which its compressed shape is admirably adapted. Blind
_Carabidae_ form a large proportion of cave-dwelling beetles, and
several species of great interest live between tide-marks along the
seashore.

The _Cicindelidae_, or tiger-beetles (figs. 7, 8) are the most highly
organized of all the Adephaga. The inner lobe (lacinia) of the first
maxilla terminates in an articulated hook, while in the second
maxillae (labium) both inner and outer lobes ("ligula" and
"para-glossae") are much reduced. The face (clypeus) is broad,
extending on either side in front of the insertion of the feelers. The
beetles are elegant insects with long, slender legs, running quickly,
and flying in the sunshine. The pronotum and elytra are often adorned
with bright colours or metallic lustre, and marked with stripes or
spots. The beetles are fierce in nature and predaceous in habit, their
sharp toothed mandibles being well adapted for the capture of small
insect-victims. The larvae are more specialized than those of other
Adephaga, the head and prothorax being very large and broad, the
succeeding segments slender and incompletely chitinized. The fifth
abdominal segment has a pair of strong dorsal hook-like processes, by
means of which the larva supports itself in the burrow which it
excavates in the earth, the great head blocking the entrance with the
mandibles ready to seize on any unwary insect that may venture within
reach.

a _Gyrinus sulcatus_ (Grooved Whirligig). Europe.
b Antenna of _Gyrinus_.
c Larva of _Gyrinus_.]

Two or three families may be regarded as aberrant Adephaga. The
_Paussidae_ are a very remarkable family of small beetles, mostly
tropical, found only in ants' nests, or flying by night, and
apparently migrating from one nest to another. The number of antennal
segments varies from eleven to two. It is supposed that these beetles
secrete a sweet substance on which the ants feed, but they have been
seen to devour the ants' eggs and grubs. The _Gyrinidae_, or whirligig
beetles (fig. 9), are a curious aquatic family with the feelers (fig.
9, b) short and reduced as in most _Paussidae_. They are flattened
oval in form, circling with gliding motion over the surface film of
the water, and occasionally diving, when they carry down with them a
bubble of air. The fore-legs are elongate and adapted for clasping,
while the short and flattened intermediate and hind legs form very
perfect oar-like propellers. The larva of _Gyrinus_ (fig. 9, c) is
slender with elongate legs, and the abdominal segments carry paired
tracheal gills.

STAPHYLINOIDEA.--The members of this tribe may be easily recognized by
their wing-nervuration. Close to a transverse fold near the base of
the wing, the median nervure divides into branches which extend to the
wing-margin; there is a second transverse fold near the tip of the
wing, and cross nervures are altogether wanting. There are four
malpighian tubes, and all five tarsal segments are usually
recognizable. With very few exceptions, the larva in this group is
active and campodeiform, with cerci and elongate legs as in the
Adephaga, but the leg has only four segments and one claw.

The _Silphidae_, or carrion beetles, form one of the best-known
families of this group. They are rotund or elongate insects with
conical front haunches, the elytra generally covering (fig. 10) the
whole dorsal region of the abdomen, but sometimes leaving as many as
four terga exposed (fig. 11). Some of these beetles are brightly
coloured, while others are dull black. They are usually found in
carrion, and the species of _Necrophorus_ (fig. 11) and _Necrophaga_
are valuable scavengers from their habit of burying small vertebrate
carcases which may serve as food for their larvae. At this work a
number of individuals are associated together. The larvae that live
underground have spiny dorsal plates, while those of the _Silpha_
(fig. 10) and other genera that go openly about in search of food
resemble wood-lice. About 1000 species of _Silphidae_ are known.
Allied to the _Silphidae_ are a number of small and obscure families,
for which reference must be made to monographs of the order. Of
special interest among these are the _Histeridae_, compact beetles
(fig. 12) with very hard cuticle and somewhat abbreviated elytra, with
over 2000 species, most of which live on decaying matter, and the
curious little _Pselaphidae_, with three-segmented tarsi, elongate
palpi, and shortened abdomen; the latter are usually found in ants'
nests, where they are tended by the ants, which take a sweet fluid
secreted among little tufts of hair on the beetles' bodies; these
beetles, which are carried about by the ants, sometimes devour their
larvae. The _Trichopterygidae_, with their delicate narrow fringed
wings, are the smallest of all beetles, while the _Platypsyllidae_
consist of only a single species of curious form found on the beaver.

The _Staphylinidae_, or rove-beetles--a large family of nearly 10,000
species--may be known by their very short elytra, which cover only two
of the abdominal segments, leaving the elongate hind-body with seven
or eight exposed, firm terga (figs. 13, 14). These segments are very
mobile, and as the rove-beetles run along they often curl the abdomen
upwards and forwards like the tail of a scorpion. The _Staphylinid_
larvae are typically campodeiform. Beetles and larvae are frequently
carnivorous in habit, hunting for small insects under stones, or
pursuing the soft-skinned grubs of beetles and flies that bore in
woody stems or succulent roots. Many _Staphylinidae_ are constant
inmates of ants' nests.

MALACODERMATA.--In this tribe may be included a number of families
distinguished by the softness of the cuticle, the presence of seven or
eight abdominal sterna and of four malpighian tubes, and the firm,
well-armoured larva (fig. 15, c) which is often predaceous in habit.
The mesothoracic epimera bound the coxal cavities of the intermediate
legs. The _Lymexylonidae_, a small family of this group, characterized
by its slender, undifferentiated feelers and feet, is believed by
Lameere to comprise the most primitive of all living beetles, and
Sharp lays stress on the undeveloped structure of the tribe generally.

The _Lampyridae_ are a large family, of which the glow-worm
(_Lampyris_) and the "soldier beetles" (_Telephorus_) are familiar
examples. The female "glow-worm" (fig. 15, b), emitting the well-known
light (see above), is wingless and like a larva; the luminosity seems
to be an attraction to the male, whose eyes are often exceptionally
well developed. Some male members of the family have remarkably
complex feelers. In many genera of _Lampyridae_ the female can fly as
well as the male; among these are the South European "fireflies."

TRICHODERMATA.--Several families of rather soft-skinned beetles, such
as the _Melyridae_, _Cleridae_ (fig. 16), _Corynetidae_, _Dermestidae_
(fig. 17), and _Dascillidae_, are included in this tribe. They may be
distinguished from the Malacodermata by the presence of only five or
six abdominal sterna, while six malpighian tubes are present in some
of the families. The beetles are hairy and their larvae well-armoured
and often predaceous. Several species of _Dermestidae_ are commonly
found in houses, feeding on cheeses, dried meat, skins and other such
substances. The "bacon beetle" (_Dermestes lardarius_), and its hard
hairy larva, are well known. According to Sharp, all Dermestid larvae
probably feed on dried animal matters; he mentions one species that
can find sufficient food in the horsehair of furniture, and another
that eats the dried insect-skins hanging in old cobwebs.

STERNOXIA.--This is an important tribe of beetles, including families
with four malpighian tubes and only five or six abdominal sterna,
while in the thorax there is a backwardly directed process of the
prosternum that fits into a mesosternal cavity. The larvae are
elongate and worm-like, with short legs but often with hard strong
cuticle.

The _Elateridae_ or click beetles (fig. 18) have the prosternal
process just mentioned, capable of movement in and out of the
mesosternal cavity, the beetles being thus enabled to leap into the
air, hence their popular name of "click-beetles" or "skip-jacks." The
prothorax is convex in front, and is usually drawn out behind into a
prominent process on either side, while the elytra are elongate and
tapering. Many of the tropical American _Elateridae_ emit light from
the spots on the prothorax and an area beneath the base of the
abdomen; these are "fireflies" (see above). The larvae of _Elateridae_
are elongate, worm-like grubs, with narrow bodies, very firm cuticle,
short legs, and a distinct anal proleg. They are admirably adapted for
moving through the soil, where some of them live on decaying organic
matter, while others are predaceous. Several of the elaterid larvae,
however, gnaw roots and are highly destructive to farm crops. These
are the well-known "wire-worms" (q.v.).

The _Buprestidae_ are distinguished from the _Elateridae_ by the
immobility of the prosternal process in the mesosternal cavity and by
the absence of the lateral processes at the hind corners of the
prothorax. Many tropical _Buprestidae_ are of large size (fig. 19),
and exhibit magnificent metallic colours; their elytra are used as
ornaments in human dress. The larvae are remarkable for their small
head, very broad thorax, with reduced legs, and narrow elongate
abdomen. They feed by burrowing in the roots and stems of plants.

BOSTRYCHOIDEA.--This tribe is distinguished from the Malacoderma and
allied groups by the mesothoracic epimera not bounding the coxal
cavities of the intermediate legs. The downwardly directed head is
covered by the pronotum, and the three terminal antennal segments form
a distinct club. To this group belong the _Bostrychidae_ and
_Ptinidae_, well known (especially the latter family) for their
ravages in old timber. The larvae are stout and soft-skinned, with
short legs in correlation with their burrowing habit. The noises made
by some _Ptinidae_ (_Anobium_) tapping on the walls of their burrows
with their mandibles give rise to the "death tick" that has for long
alarmed the superstitious.

CLAVICORNIA.--This is a somewhat heterogeneous group, most of whose
members are characterized by clubbed feelers and simple, unbroadened
tarsal segments--usually five on each foot--but in some families and
genera the males have less than the normal number on the feet of one
pair. There are either four or six malpighian tubes. A large number of
families, distinguished from each other by more or less trivial
characters, are included here, and there is considerable diversity in
the form of the larvae. The best-known family is the _Hydrophilidae_,
in which the feelers are short with less than eleven segments and the
maxillary palpi very long. Some members of this family--the large
black _Hydrophilus piceus_ (fig. 20), for example--are specialized for
an aquatic life, the body being convex and smooth as in the
_Dyticidae_, and the intermediate and hind-legs fringed for swimming.
When _Hydrophilus_ dives it carries a supply of air between the elytra
and the dorsal surface of the abdomen, while air is also entangled in
the pubescence which extends beneath the abdomen on either side, being
scooped in bubbles by the terminal segments of the feelers when the
insect rises to the surface. Many of the _Hydrophilidae_ construct,
for the protection of their eggs, a cocoon formed of a silky material
derived from glands opening at the tip of the abdomen. That of
_Hydrophilus_ is attached to a floating leaf, and is provided with a
hollow, tapering process, which projects above the surface and
presumably conveys air to the enclosed eggs. Other _Hydrophilidae_
carry their egg-cocoons about with them beneath the abdomen. Many
_Hydrophilidae_, unmodified for aquatic life, inhabit marshes. The
larvae in this family are well-armoured, active and predaceous. Of the
numerous other families of the Clavicornia may be mentioned the
_Cucujidae_ and _Cryptophagidae_, small beetles, examples of which may
be found feeding on stored seeds or vegetable refuse, and the
_Mycetophagidae_, which devour fungi. The _Nitidulidae_ are a large
family with 1600 species, among which members of the genus
_Meligethes_ are often found in numbers feeding on blossoms, while
others live under the bark of trees and prey on the grubs of boring
beetles.

HETEROMERA.--This tribe is distinguished by the presence of the normal
five segments in the feet of the fore and intermediate legs, while
only four segments are visible in the hind-foot. Considerable
diversity is to be noticed in details of structure within this group,
and for an enumeration of all the various families which have been
proposed and their distinguishing characters the reader is referred to
one of the monographs mentioned below. Some of the best-known members
of the group belong to the _Tenebrionidae_, a large family containing
over 10,000 species and distributed all over the world. The
tenebrionid larva is elongate, with well-chitinized cuticle, short
legs and two stumpy tail processes, the common mealworm (fig. 21)
being a familiar example. Several species of this family are found
habitually in stores of flour or grain. The beetles have feelers with
eleven segments, whereof the terminal few are thickened so as to form
a club. The true "black-beetles" or "churchyard beetles" (_Blaps_)
(fig. 22) belong to this family; like members of several allied genera
they are sooty in colour, and somewhat resemble ground beetles
(_Carabi_) in general appearance.

The most interesting of the Heteromera, and perhaps of all the
Coleoptera, are some beetles which pass through two or more larval
forms in the course of the life-history (hypermetamorphosis). These
belong to the families _Rhipidophoridae_ and _Meloidae_. The latter
are the oil beetles (fig. 23) or blister beetles (fig. 24), insects
with rather soft cuticle, the elytra (often abbreviated) not fitting
closely to the sides of the abdomen, the head constricted behind the
eyes to form a neck, and the claws of the feet divided to the base.
Several of the _Meloidae_ (such as the "Spanish fly," fig. 24) are of
economic importance, as they contain a vesicant substance used for
raising medicinal blisters on the human skin. The wonderful
transformations of these insects were first investigated by G. Newport
in 1851, and have recently been more fully studied by C. V. Riley
(1878) and J. H. Fabre. The first larval stage is the "triungulin," a
tiny, active, armoured larva with long legs (each foot with three
claws) and cercopods. In the European species of _Sitaris_ and _Meloe_
these little larvae have the instinct of clinging to any hairy object.
All that do not happen to attach themselves to a bee of the genus
_Anthophora_ perish, but those that succeed in reaching the right host
are carried to the nest, and as the bee lays an egg in the cell the
triungulin slips off her body on to the egg, which floats on the
surface of the honey. After eating the contents of the egg, the larva
moults and becomes a fleshy grub with short legs and with paired
spiracles close to the dorsal region, so that, as it floats in and
devours the honey, it obtains a supply of air. After a resting
(pseudo-pupal) stage and another larval stage, the pupa is developed.
In the American EPICAUTA VITTATA the larva is parasitic on the eggs
and egg-cases of a locust. The triungulin searches for the eggs, and,
after a moult, becomes changed into a soft-skinned tapering larva.
This is followed by a resting (pseudo-pupal) stage, and this by two
successive larval stages like the grub of a chafer. The
RHIPIDOPHORIDAE are beetles with, short elytra, the feelers pectinate
in the males and serrate in the females. The life-history of
_Metoecus_ has been studied by T. A. Chapman, who finds that the eggs
are laid in old wood, and that the triungulin seeks to attach itself
to a social wasp, who carries it to her nest. There it feeds first as
an internal parasite of the wasp-grub, then bores its way out, moults
and devours the wasp larva from outside. The wasps are said to leave
the larval or pupal _Metoecus_ unmolested, but they are hostile to the
developed beetles, which hasten to leave the nest as soon as possible.