Chapter XXIII: Act 1737: , and the Apportionment Act 1834, and is now allowed generally (14)

Sub-order a. Laniatores.--Orifice of foetid glands opening above the
coxa of the 4th appendage, not raised upon a tubercle. Orifice of
coxal gland situated just behind that of the foetid gland. Sternal
plate of prosoma long and narrow, with a distinct prosternal element
underlying the mouth. Coxae of 4th, 5th and 6th appendages immovable.
Appendages of 2nd pair, strong, usually prehensile and spiny. Genital
orifice covered by an operculum.

Families--Gonoleptidae (_Gonoleptes, Goniasoma_).
Biantidae (_Biantes_).
Oncopodidae (_Oncopus, Pelitnus_).
Trioenonychidae (_Trioenonyx, Acumontia_).

Sub-order b. Palpatores.--Orifice of foetid glands opening above the
coxa of the 3rd appendage, not raised upon a tubercle. Orifice of
coxal gland situated between the coxae of the 5th and 6th appendages.
Sternal plate of prosoma usually short and wide, rarely longer than
broad; with a larger or smaller prosternal element underlying the
mouth. Coxae of 3rd, 4th, 5th and 6th appendages movable or
immovable. Appendages of 2nd pair weak, pediform not prehensile.
Genital orifice covered by an operculum.

Families--Phalangiidae (_Phalangium, Gagrella_).
Ischyropsalidae (_Ischyropsalis, Taracus_).
Nemastomidae (_Nemastoma_).
Trogulidae (_Trogulus, Anelasmocephalus_).

Sub-order c. _Cyphophthalmi_ (_Anepignathi_).--Orifice of foetid
glands opening on a tubercle situated near the lateral border of the
carapace above the base of the 5th appendage. Orifice of coxal gland
probably situated at base of coxa of 5th appendage; sternal plate of
prosema minute or absent; no prosternal element underlying the mouth.
Coxae of 5th and 6th, and usually also of 4th appendages immovable.
Appendages of 2nd pair weak, pediform, not prehensile. Genital orifice
not covered by an operculum.

Families--Sironidae (_Siro, Pettalus_).
Stylocellidae (_Stylocellus_).

_Remarks on the Opiliones._--These include the harvest-men, sometimes
called also daddy-long-legs, with round undivided bodies and very
long, easily-detached legs. The intromittent organs of the male are
remarkable for their complexity and elaboration. The confluence of the
regions of the body and the dislocation of apertures from their
typical position are results of degeneration. The Opiliones seem to
lead on from the Spiders to the Mites. Reference to literature (39).

A, Dorsal view; I to VI, the six prosomatic appendages.
B, Ventral view of the prosoma and of the first somite of the
opisthosoma, with the appendages I to VI cut off at the base; a,
tracheal stigma; mx, maxillary processes of the coxae of the 3rd
pair of appendages; g, genital aperture.
C, Ventral surface of the prosoma and opisthosoma; a, tracheal
stigma; b, last somite.
D, Lateral view of the 1st and 2nd pair of appendages.
E, Lateral view of the whole body and two 1st appendages, showing
the fusion of the dorsal elements of the prosoma into a single
plate, and of those of the opisthosoma into an imperfectly
segmented plate continuous with that of the prosoma.]

Apparently related to the Opiliones are two extinct groups, the
Anthracomarti and Phalangiotarbi, which are not known to have survived
the Carboniferous period. In the Anthracomarti the opisthosoma was
movably articulated to the prosoma, and consisted of from eight to ten
segments furnished with movable lateral plates, the anal segment being
overlapped dorsally by a laminate expansion of the preceding segment.
The carapace of the prosoma was unsegmented and often bore a pair of
eyes. The appendages of the 2nd pair were slender and pediform; those
of the 3rd, 4th, 5th and 6th pairs were similar in form and ambulatory
in function with their basal segments arranged round a sternal area as
in the order Araneae. The best-known genera were _Anthracomartus_ and
_Eophognus_.

In the Phalangiotarbi the appendages resembled those of the
Anthracomarti, except that the basal segments of the last four pairs
were usually approximated in the middle line leaving a long and narrow
sternal area between; and the carapace of the prosoma was unsegmented.
The prosoma and opisthosoma were broadly confluent and probably
immovably welded together. The opisthosoma consisted of eight or nine
segments, whereof the anterior five or six were very short in the
dorsal region, and the posterior three exceptionally large with the
anal orifice terminal.

Several genera have been established, the best-characterized being
_Geraphognus_ and _Architarbus_.

Order 9. Rhynchostomi = Acari (see fig. 78).--Degenerate Arachnids
resembling the Opiliones in many structural points, but chiefly
distinguishable from them by the following features:--The basal
segments of the appendages of the 2nd pair are united in the middle
line behind the mouth, those of the 3rd, 4th, 5th and 6th pairs are
widely separated and not provided with sterno-coxal (maxillary) lobes,
and take no share in mastication; the respiratory stigmata, when
present, belong to the prosoma, and the primitive segmentation of the
opisthosoma has entirely or almost entirely disappeared.

Sub-order a. _Notostigmata._--Opisthosoma consisting of ten segments
defined by integumental grooves, each of the anterior four of these
furnished with a single pair of dorsally-placed spiracles or tracheal
stigmata.

Family--Opilioacaridae (_Opilioacarus_).

Sub-order b. _Cryptostigmata._--Integument hard, strengthened by a
continuously chitinized dorsal and ventral sclerite. Tracheae
typically opening by stigmata situated in the articular sockets
(acetabula) of the 3rd, 4th, 5th and 6th pairs of appendages.

Family--Oribatidae (_Oribata, Nothrus, Hoplophora_).

Sub-order c. _Metastigmata._--Integument mostly like that of the
Cryptostigmata. Tracheae opening by a pair of stigmata situated above
and behind the base of the 4th or 5th or 6th pair of appendages.

Families--Gamasidae (_Gamasus, Pteroptus_).
Argasidae (_Argas, Ornithodoros_).
Ixodidae (_Ixodes, Rhipicephalus_).

Sub-order d. _Prostigmata._--Integument soft, strengthened by special
sclerites, those on the ventral surface of the prosoma apparently
representing the basal segments of the legs embedded in the skin.
Tracheae, except in the aquatic species in which they are atrophied,
opening by a pair of stigmata situated close to or above the base of
the appendages of the 1st pair (mandibles).

Families--Trombidiidae (_Trombidium, Tetranychus_).
Hydrachnidae (_Hydrachna, Atax_).
Halacaridae (_Halacarus, Leptognathus_).
Bdellidae (_Bdella, Eupodes_).

A, Lateral view with appendages III to VI removed; 1, plate covering
the whole dorsal area, representing the fused tergal sclerites of
the prosoma and opisthosoma; 2, similarly-formed ventral plate; 3,
tracheal stigma.
B, Dorsal view of the same animal; II to VI, 2nd to 6th pairs of
appendages. The 1st pair of appendages both in this and in C are
retracted.
C, Ventral view of the same; II to VI as in B; a, genital orifice;
b, anus; c, united basal segments of the second pair of appendages;
d, basal segment of the 6th prosomatic appendage of the right side.
The rest of the appendage, as also of app. Ill, IV and V, has been
cut away.]

Sub-order e. _Astigmata._--Degenerate, mostly parasitic forms
approaching the Prostigmata in the development of integumental
sclerites and the softness of the skin, but with the respiratory
system absent.

Families--Tyroglyphidae (_Tyroglyphus, Rhizoglyphus_).
Sarcoptidae (_Sarcoptes, Analges_).

Sub-order f. _Vermiformia._--Degenerate atracheate parasitic forms
with the body produced posteriorly into an annulated caudal
prolongation, and the 3rd, 4th, 5th and 6th pairs of appendages short
and only three-jointed.

Family--Demodicidae (_Demodex_).

Sub-order g. _Tetrapoda._--Degenerate atracheate gall-mites in which
the body is produced posteriorly and annulated, as in _Demodex_, but
in which the appendages of the 3rd and 4th pairs are long and normally
segmented and those of the 5th and 6th pairs entirely absent.

Family--Eriophyidae (_Eriophyes, Phyllocoptes_).

_Remarks on the Rhynchostomi._--The Acari include a number of forms
which are of importance and special interest on account of their
parasitic habits. The ticks (_Ixodes_) are not only injurious as
blood-suckers, but are now credited with carrying the germs of Texas
cattle-fever, just as mosquitoes carry those of malaria. The
itch-insect (_Sarcoptes scabiei_) is a well-known human parasite, so
minute that it was not discovered until the end of the 18th century,
and "the itch" was treated medicinally as a rash. The female burrows
in the epidermis much as the female trap-door spider burrows in turf
in order to make a nest in which to rear her young. The male does not
burrow, but wanders freely on the surface of the skin. _Demodex
folliculorum_ is also a common parasite of the sebaceous glands of
the skin of the face in man, and is frequent in the skin of the dog.
Many Acari are parasitic on marine and freshwater molluscs, and others
are found on the feathers of birds and the hair of mammals. Others
have a special faculty of consuming dry, powdery vegetable and animal
refuse, and are liable to multiply in manufactured products of this
nature, such as mouldy cheese. A species of Acarus is recorded as
infesting a store of powdered strychnine and feeding on that drug, so
poisonous to larger organisms. Reference to literature (40).

AUTHORITIES cited by numbers in the text.--1. Strauss-Durckheim (as
reported by MM. Riester and Sanson in an appendix to the sixth volume
of the French translation of Meckel's _Anatomy_, 1829); 2. Lankester,
"Limulus an Arachnid," _Quart. Journ. Micr. Sci._ vol. xxi. N.S.,
1881; 3. _Idem_, "On the Skeletotrophic Tissues of Limulus, Scorpio
and Mygale," _Quart. Journ. Micr. Sci._ vol. xxiv. N.S., 1884; 4.
_Idem. Trans. Zool. Soc._ vol. xi., 1883; 5. Lankester and A.G.
Bourne, "Eyes of Limulus and Scorpio," _Quart. Journ. Micr. Sci._ vol.
xxiii. N.S., Jan. 1883; 6. Milne-Edwards, A., "Recherches sur
l'anatomie des Limules," _Ann. Sci. Nat._ 5th Series, _Zoologie_, vol.
xvii., 1873; 7. Owen, Richard, "Anatomy of the King-Crab," _Trans.
Linn. Soc. Lond._, vol. xxviii., 1872; 8. Kishinouye, "Development of
_Limulus longispina_," _Journal of the Science College of Japan_, vol.
v., 1892; 9. Brauer, "Development of Scorpion," _Zeitschrift fur wiss.
Zoologie_, vol. lix., 1895; 10. Hansen, H.J., "Organs and Characters
in Different Orders of Arachnida," _Entomol. Meddel._ vol. iv. pp.
137-149; 11. Watase, "On the Morphology of the Compound Eyes of
Arthropods," _Studies from the Biolog. Lab. Johns Hopkins University_,
vol. iv. pp 287-334; 12. Newport, George, "Nervous and Circulatory
Systems in Myriapoda and Macrourous Arachnids," _Phil. Trans. Roy.
Soc._, 1843; 13. Lankester, "Coxal Glands of Limulus, Scorpio and
Mygale," _Quart. Journ. Micr. Sci._ vol. xxiv. N.S., 1884; 13A. W.
Patten and A.P. Hazen, "Development of the Coxal Glands of Limulus,"
_Journ. of Morphology_, vol. xvi., 1900; 13B. Bernard, "Coxal Glands
of Scorpio," _Ann. and Mag. Nat. Hist._ vol. xii., 1893, p. 55; 14.
Benham, "Testis of Limulus," _Trans. Linn. Soc._, 1882; 15. Lankester,
"Mobility of the Spermatozoa of Limulus," _Quart. Journ. Micr. Sci._
vol. xviii. N.S., 1878; 16. Korschelt and Heider,
_Entwickelungsgeschichte_ (Jena, 1892), _ibique citata_; 17. Laurie,
M., "The Embryology of a Scorpion," _Quart. Journ. Micr. Sci._ vol.
xxxi. N.S., 1890, and "On Development of _Scorpio fulvipes_," _ibid._
vol. xxxii., 1891; 18. Lankester (Homoplasy and Homogeny), "On the Use
of the term Homology in Modern Zoology," _Ann. and Mag. Nat. Hist._,
1870; 19. _Idem_, "Degeneration, a Chapter in Darwinism," 1878,
reprinted in the _Advancement of Science_ (Macmillan, 1890); 20.
_Idem_, "Limulus an Arachnid," _Q. J. Micr. Sci._ vol. xxi. N.S.; 21.
Claus, "Degeneration of the Acari and Classification of Arthropoda,"
_Anzeiger d. k. k. Akad. Wissen. Wien_, 1885; see also _Ann. and Mag.
Nat. Hist._ (5) vol. xvii., 1886, p. 364, and vol. xix. p. 225; 22.
Lindstrom, G., "Researches on the Visual Organs of the Trilobites,"
_K. Svenska Vet. Akad. Handl._ xxxiv. No. 8, pp. 1-86, Pls. i.-vi.,
1901; 22*. Zittel, American edition of his _Palaeontology_ (the
Macmillan Co., New York), where ample references to the literature of
Trilobitae and Eurypteridae will be found; also references to
literature of fossil Scorpions and Spiders; 23. Hoek, "Report on the
Pycnogonida," _Challenger Expedition Reports_, 1881; Meinert,
"Pycnogonida of the Danish Ingolf Expedition," vol. iii., 1899;
Morgan, "Embryology and Phylogeny of the Pycnogonids," _Biol. Lab.
Baltimore_, vol. v., 1891; 24. Bourne, A.G., "The Reputed Suicide of
the Scorpion," _Proc. Roy. Soc._ vol. xlii. pp. 17-22; 25. Lankester,
"Notes on some Habits of Scorpions," _Journ. Linn. Soc. Zool._ vol.
xvi. p. 455, 1882; 26. Huxley, "Pharynx of Scorpion," _Quart. Journ.
Micr. Sci._ vol. viii. (old series), 1860, p. 250; 27. Pocock, "How
and Why Scorpions hiss," _Natural Science_, vol. ix., 1896; cf.
_idem_, "Stridulating Organs of Spiders," _Ann. and Mag. Nat. Hist._
(6), xvi. pp. 230-233; 28. Kraepelin, _Das Thierreich (Scorpiones et
Pedipalpi_) (Berlin, 1899); Peters, "Eine neue Eintheilung der
Skorpione," _Man. Akad. Wiss. Berlin_, 1861; Pocock, "Classification
of Scorpions," _Ann. and Mag. Nat. Hist._ (6) xii., 1893; Thorell and
Lindstrom, "On a Silurian Scorpion," _Kongl. Svens. Vet. Akad. Handl._
xxi. No. 9, 1885; 29. Cambridge, O.P., "A New Family (Tartarides) and
Genus of Thelyphonidea," _Ann. and Mag. Nat. Hist._ (4) x., 1872, p.
413; Cook, "Hubbardia, a New Genus of Pedipalpi," _Proc. Entom. Soc.
Washington_, vol. iv., 1899; Thorell, "Tartarides, &c." _Ann. Mus.
Genova_, vol. xxvii., 1889; 30. M Cook, _American Spiders and their
Spinning Work_ (3 vols.; Philadelphia, 1889-1893); 31. Peckham, "On
Sexual Selection in Spiders," _Occasional Papers Nat. Hist. Soc.
Wisconsin_, vol. i. pp. 1-113, 1889; 32. Moggridge, _Harvesting Ants
and Trap-Door Spiders_ (1873); 33. Bertkau, Ph., _Arch. f.
Naturgesch._ vol. xlviii. pp. 316-362; _Idem_, same journal, 1875, p.
235, and 1878, p. 351; Cambridge, O.P., "Araneidea" in _Biologia
Centr. Americana_, vols. i. and ii. (London, 1899); Keyserling,
_Spinnen Amerikas_ (Nuremberg, 1880-1892); Pocock, "Liphistius and the
Classification of Spiders," _Ann. and Mag. Nat. Hist._ (6) x., 1892;
Simon, _Hist. nat. des Araignees_, vols. i. and ii., 1892, 1897;
Wagner, "L'Industrie des Araneina," _Mem. Acad. St-Petersbourg_;
_Idem_, "La Mue des Araignees," _Ann. Sci. Nat._ vol. vi.; 34. Grassi,
G.B. "Intorno ad un nuovo Aracnide artrogastro (_Koenenia mirabilis_)
&c." _Boll. Soc. Ent. Ital._ vol. xviii., 1886; 35. H.J. Hansen and
Sorensen, "The Order Palpigradi, Thorell (_Koenenia_), and its
Relationships with other Arachnida," _Ent. Tidskr._ vol. xviii. pp.
233-240, 1898; Kraepelin, _Das Thierreich_ (Berlin, 1901); 36.
Bernard. "Compar. Morphol. of the Galeodidae," _Trans. Linn. Soc.
Zool._ vol. vi., 1896, _ibique citata_; Dufour, "Galeodes," _Mem.
pres. Acad. Sci. Paris_, vol. xvii., 1862; Kraepelin, _Das Thierreich_
(Berlin, 1901); Pocock, "Taxonomy of Solifugae," _Ann. and Mag. Nat.
Hist._ vol. xx.; 37. Balzan, "Voyage au Venezuela (Pseudoscorpiones),"
_Ann. Soc. Entom. France_, 1891, pp. 497-522; 38. Guerin-Meneville,
_Rev. Zool._, 1838, p. II; Karsch, "Ueber Cryptostemma Guer."
_Berliner entom. Zeitschrift_, xxxviii. pp. 25-32, 1892; Thorell, "On
an apparently new Arachnid belonging to the family _Cryptostemmidae_,"
_Westv. Bihang Svenska Vet. Akad. Handligar_, vol. xvii. No. 9, 1892;
39. Hansen and Sorensen, _On Two Orders of Arachnida_ (Cambridge,
1904); Sorensen, "_Opiliones laniatores_," _Nat. Tidskr._ (3) vol.
xiv., 1884; Thorell, "Opilioni," _Ann. Mus. Genova_, vol. viii., 1876;
40. Berlese, "Acari, &c., in Italia reperta" (Padova, 1892);
Canestrini, _Acarofauna Italiana_ (Padova, 1885); Canestrini and
Kramer, "Demodicidae and Sarcoptidae" in _Das Thierreich_ (Berlin,
1899); Michael, "British Oribatidae," _Ray Soc._; _Idem_, "Oribatidae"
in _Das Thierreich_ (Berlin, 1898); _Idem_, "Progress and Present
State of Knowledge of Acari," _Journ. Roy. Micr. Soc._, 1894; Nalepa,
"Phytoptidae," _Das Thierreich_ (Berlin, 1898); Trouessart,
"Classification des Acariens," _Rev. Sci. Nat. de l'ouest._ p. 289,
1892; Wagner, _Embryonal Entwick, von Ixodes_ (St Petersburg, 1803);
41. Bertkau, Ph., "Coxaldrusen der Arachniden," _Sitzb. Niederl.
Gesellsch._, 1885; 42. Patten, W., "Brain and Sense Organs of
Limulus," _Quart. Journ. Mic. Sci._ vol. xxxv., 1894; see also his
"Origin of Vertebrates from Arachnids," _ibid._ vol. xxxi.

Authorities not cited by numbers in the text:--

Lung-books:--Berteaux, "Le Poumon des Arachnides," _La Cellule_, vol.
v. 1891; Jawarowski, "Die Entwick. d. sogen. Lunge bei der
Arachniden," _Zeitsch. wiss. Zool._ vol. lviii., 1894; Macleod,
"Recherches sur la structure et la signification de l'appareil
respiratoire des Arachnides," _Arch. d. Biologie._ vol. v., 1884;
Schneider, A., "Melanges arachnologiques," in _Tablettes zoologiques_,
vol. ii. p. 135, 1892; Simmons, "Development of Lung in Spiders,"
_Amer. Journ. Science_, vol. xlviii., 1894. Coxal Glands:--Bertkau,
"Ueber die Coxaldrusen der Arachniden," _Sitzb. d. Niederl.
Gesellsch._, 1885; Loman, "Altes und neues uber das Nephridium (die
Coxaldruse) der Arachniden," _Byd. tot de Dierkunde_, vol. xiv., 1887;
Macleod, "Glande coxale chez les Galeodes," _Bull. Acad. Belg._ (3)
vol. viii., 1884; Pelseneer, "On the Coxal Glands of Mygale," _Proc.
Zool. Soc._, 1885; Tower, "The External Opening of the brick-red
Glands of Limulus," _Zool. Anzeiger_, vol. xviii. p. 471, 1895.
Ento-sternite:--Schimkewitsch, "Bau und Entwick. des Endosternites der
Arachniden," _Zool. Jahrb._, Anal. Abtheil., vol. viii., 1894.
Embryology:--Balfour, "Development of the Araneina," _Q. J. Micr.
Sci._ vol. xx., 1880; Kingsley, "The Embryology of Limulus," _Journ.
Morphology_, vols. vii. and viii.; Kishinouye, "Development of
Araneina," _Journ. Coll. Sci. Univ. of Japan_, vol. iv., 1890; Locy,
"Development of Agelena," _Bull. Mus. Harvard_, vol. xii., 1885;
Metchnikoff, "Embryologie d. Scorpion," _Zeit. wiss. Zool._ vol. xxi.,
1871; _Idem_, "Embryol. Chelifer," _Zeit. wiss. Zool._ vol. xxi.,
1871; Schimkewitsch, "Developpement des Araignees," _Archives d.
Biologie_, vol. vi. 1887. Sense organs:--Bertkau, "Sinnesorgane der
Spinnen," _Arch. f. mikros. Anat._ vol. xxvii. p. 589, 1886; Graber,
"Unicorneale Tracheaten Auge," _Arch. f. mikr. Anat._ vol. xvii.,
1879; Grenacher, _Gehororgane der Arthropoden_ (Gottingen, 1879);
Kishinouye, "Lateral Eyes of Spiders," _Zool. Anz._ vol. xiv. p. 381,
1891; Purcell, "Phalangiden Augen," _Zool. Anzeiger_, vol. xv. p. 461.

General works on Arachnida:--Blanchard, "Les Arachnides" in
_L'Organisation du regne animal_; Gaubert, "Recherches sur les
Arachnides," _Ann. Sci. Nat._ (7) vol. xiii., 1892; Koch, C., _Die
Arachniden_ (16 vols., Nuremberg, 1831-1848); Koch, Keyserling and
Sorensen, _Die Arachniden Australiens_ (Nuremberg, 1871-1890); Pocock,
_Arachnida of British India_ (London, 1900); _Idem_, "On African
Arachnida," in _Proc. Zool. Soc._ and _Ann. and Mag. Nat. Hist._,
1897-1900; Simon, _Les Arachnides de la France_ (7 vols., Paris,
1874-1881); Thorell, "Arachnida from the Oriental Region," _Ann. Mus.
Genova_, 1877-1899. (E. R. L.)

FOOTNOTES:

[1] See the article ARTHROPODA for the use of the term "prosthomere."

[2] See fig. 12 in the article ARTHROPODA.

[3] Though ten is the prevailing number of retinula cells and
rhabdomeres in the lateral eye of Limulus, Watase states that they
may be as few as nine and as many as eighteen.

[4] A great deal of superfluous hypothesis has lately been put
forward in the name of "the principle of convergence of characters"
by a certain school of palaeontologists. The horse is supposed by
these writers to have originated by separate lines of descent in the
Old World and the New, from five-toed ancestors! And the important
consequences following from the demonstration of the identity in
structure of Limulus and Scorpio are evaded by arbitrary and even
phantastic invocations of a mysterious transcendental force which
brings about "convergence" irrespective of heredity and selection.
Morphology becomes a farce when such assumptions are made. (E. R. L.)

[5] A pair of round tubercles on the labram (camerostome or
hypostoma) of several species of Trilobites has been described and
held to be a pair of eyes (22). Sense-organs in a similar position
were discovered in Limulus by Patten (42) in 1894.

[6] The writer is indebted to R.I. Pocock, assistant in the Natural
History departments of the British Museum, for valuable assistance in
the preparation of this article and for the classification and
definition of the groups of Eu-arachnida here given. The general
scheme and some of the details have been brought by the writer into
agreement with the views maintained in this article. Pocock accepts
those views in all essential points and has, as a special student of
the Arachnida, given to them valuable expansion and confirmation. The
writer also desires to express his thanks to Messrs. Macmillan & Co.
for permission to use figs. 22, 43, 44 and 45, which are taken from
Parker and Haswell's _Text-book of Zoology_; and to Messrs. Swan
Sonnenschein & Co. for the loan of several figures from the
translations published by them of the admirable treatise on
_Embryology_ by Professors Korschelt and Heider; also to the
publishers of the treatise on _Palaeontology_ by Professor Zittel,
Herr Oldenbourg and The Macmillan Co., New York, for several cuts of
extinct forms.

[7] Pocock suggests that the area marked vii. in the outline figure
of the dorsal view of _Limulus_ (fig. 7) may be the tergum of the
suppressed prae-genital somite. Embryological evidence must settle
whether this is so or not.

ARAD, or O-ARAD, a town of Hungary, capital of the county of the same name, 159 m. S.E. of Budapest by rail. Pop. (1900) 53,903. It is situated on the right bank of the river Maros, and consists of the inner town and five suburbs. Arad is a modern-built town, and contains many handsome private and public buildings, including a cathedral. It is the seat of a Greek-Orthodox bishop, and possesses a Greek-Orthodox theological seminary, two training schools for teachers--one Hungarian, and the other Rumanian--and a conservatoire for music. The town played an important part in the Hungarian revolution of 1848-49, and possesses a museum containing relics of this war of independence. One of the public squares contains a martyrs' monument, erected in memory of the thirteen Hungarian generals shot here on the 6th of October 1849, by order of the Austrian general Haynau. It consists of a colossal figure of Hungary, with four allegorical groups, and medallions of the executed generals. Arad is an important railway junction, and has become the largest industrial and commercial centre of south-eastern Hungary. Its principal industries are: distilling, milling, machinery-making, leather-working and saw-milling. A large trade is carried on in grain, flour, alcohol, cattle and wood. Arad was a fortified place, and was captured by the Turks during the wars of the 17th century, and kept by them till the end of that century. The new fortress, built in 1763, although small, was formidable, and played a great role during the Hungarian struggle for independence in 1849. Bravely defended by the Austrian general Berger until the 1st of July 1849, it was then captured by the Hungarian rebels, who made it their headquarters during the latter part of the insurrection. It was from it that Kossuth issued his famous proclamation (11th August 1849), and it was here that he handed over the supreme military and civil power to Gorgei. The fortress was recaptured shortly after the surrender of Gorgei to the Russians at Vilagos. The fortress is now used as an ammunition depot.

The town of Uj-Arad, i.e. New Arad (pop. 6124), situated on the opposite bank of the Maros, is practically a suburb of Arad, with which it is connected by a bridge. The town was founded during the Turkish wars of the 17th century. The works erected by the Turks for the capture of the fortress of Arad formed the nucleus of the new town.

Vilagos, the town where the famous capitulation of Gorgei to the Russians took place on the 13th of August 1849, lies 21 m. by rail north-east of Arad.

ARAEOSTYLE (Gr. [Greek: araios], weak or widely spaced, and [Greek: stylos], column), an architectural term for the intercolumniation (q.v.) given to those temples where the columns had only timber architraves to carry.

ARAEOSYSTYLE (Gr. [Greek: araios], widely spaced, and [Greek: systylos], with columns set close together), an architectural term applied to a colonnade, in which the intercolumniation (q.v.) is alternately wide and narrow, as in the case of the western porch of St Paul's cathedral and the east front of the Louvre by Perrault.

ARAGO, DOMINIQUE FRANCOIS JEAN (1786-1853), French physicist, was born on the 26th of February 1786, at Estagel, a small village near Perpignan, in the department of the eastern Pyrenees. He was the eldest of four brothers. Jean (1788-1836) emigrated to America and became a general in the Mexican army. Jacques Etienne Victor (1799-1855) took part in L.C. de S. de Freycinet's exploring voyage in the "Uranie" from 1817 to 1821, and on his return to France devoted himself to journalism and the drama. The fourth brother, Etienne Vincent (1802-1892), is said to have collaborated with H. de Balzac in the _Heritiere de Birague_, and from 1822 to 1847 wrote a great number of light dramatic pieces, mostly in collaboration. A strong republican, he was obliged to leave France in 1849, but returned after the amnesty of 1859. In 1879 he was nominated director of the Luxembourg museum.

Showing decided military tastes Francois Arago was sent to the municipal college of Perpignan, where he began to study mathematics in preparation for the entrance examination of the polytechnic school. Within two years and a half he had mastered all the subjects prescribed for examination, and a great deal more, and, on going up for examination at Toulouse, he astounded his examiner by his knowledge of Lagrange. Towards the close of 1803 he entered the polytechnic school, with the artillery service as the aim of his ambition, and in 1804, through the advice and recommendation of S.D. Poisson, he received the appointment of secretary to the Observatory of Paris. He now became acquainted with Laplace, and through his influence was commissioned, with J.B. Biot, to complete the meridional measurements which had been begun by J.B.J. Delambre, and interrupted since the death of P.F.A. Mechain (1744-1804). The two left Paris in 1806 and began operations among the mountains of Spain, but Biot returned to Paris after they had determined the latitude of Formentera, the southernmost point to which they were to carry the survey, leaving Arago to make the geodetical connexion of Majorca with Ivica and with Formentera.

The adventures and difficulties of the latter were now only beginning. The political ferment caused by the entrance of the French into Spain extended to these islands, and the ignorant populace began to suspect that Arago's movements and his blazing fires on the top of Mount Galatzo were telegraphic signals to the invading army. Ultimately they became so infuriated that he was obliged to cause himself to be incarcerated in the fortress of Belver in June 1808. On the 28th of July he managed to escape from the island in a fishing-boat, and after an adventurous voyage he reached Algiers on the 3rd of August. Thence he procured a passage in a vessel bound for Marseilles, but on the 16th of August, just as the vessel was nearing Marseilles, it fell into the hands of a Spanish corsair. With the rest of the crew, Arago was taken to Rosas, and imprisoned first in a windmill, and afterwards in the fortress of that seaport, until the town fell into the hands of the French, when the prisoners were transferred to Palamos. After fully three months' imprisonment they were released on the demand of the dey of Algiers, and again set sail for Marseilles on the 28th of November, but when within sight of their port they were driven back by a northerly wind to Bougie on the coast of Africa. Transport to Algiers by sea from this place would have occasioned a weary stay of three months; Arago, therefore, set out for it by land under conduct of a Mahommedan priest, and reached it on Christmas day. After six months' stay in Algiers he once again, on the 21st of June 1809, set sail for Marseilles, where he had to undergo a monotonous and inhospitable quarantine in the lazaretto, before his difficulties were over. The first letter he received, while in the lazaretto, was from A. von Humboldt; and this was the origin of a connexion which, in Arago's words, "lasted over forty years without a single cloud ever having troubled it."

Through all these vicissitudes Arago had succeeded in preserving the records of his survey; and his first act on his return home was to deposit them in the Bureau des Longitudes at Paris. As a reward for his adventurous conduct in the cause of science, he was in September 1809 elected a member of the Academy of Sciences, in room of J.B.L. Lalande, at the remarkably early age of twenty-three, and before the close of the same year he was chosen by the council of the polytechnic school to succeed G. Monge in the chair of analytical geometry. About the same time he was named by the emperor one of the astronomers of the Royal Observatory, which was accordingly his residence till his death, and it was in this capacity that he delivered his remarkably successful series of popular lectures on astronomy, which were continued from 1812 to 1845.

In 1816, along with Gay-Lussac, he started the _Annales de chimie et de physique_, and in 1818 or 1819 he proceeded along with Biot to execute geodetic operations on the coasts of France, England and Scotland. They measured the length of the seconds-pendulum at Leith, and in Unst, one of the Shetland isles, the results of the observations being published in 1821, along with those made in Spain. Arago was elected a member of the Board of Longitude immediately afterwards, and contributed to each of its _Annuals_, for about twenty-two years, important scientific notices on astronomy and meteorology and occasionally on civil engineering, as well as interesting memoirs of members of the Academy.

In 1830, Arago, who always professed liberal opinions of the extreme republican type, was elected a member of the chamber of deputies for the Lower Seine, and he employed his splendid gifts of eloquence and scientific knowledge in all questions connected with public education, the rewards of inventors, and the encouragement of the mechanical and practical sciences. Many of the most creditable national enterprises, dating from this period, are due to his advocacy--such as the reward to L.J.M. Daguerre for the invention of photography, the grant for the publication of the works of P. Fermat and Laplace, the acquisition of the museum of Cluny, the development of railways and electric telegraphs, the improvement of the navigation of the Seine, and the boring of the artesian wells at Grenelle.

In the year 1830 also he was appointed director of the Observatory, and as a member of the chamber of deputies he was able to obtain grants of money for rebuilding it in part, and for the addition of magnificent instruments. In the same year, too, he was chosen perpetual secretary of the Academy of Sciences, in room of J.B.J. Fourier. Arago threw his whole soul into its service, and by his faculty of making friends he gained at once for it and for himself a world-wide reputation. As perpetual secretary it fell to him to pronounce historical _eloges_ on deceased members; and for this duty his rapidity and facility of thought, his happy piquancy of style, and his extensive knowledge peculiarly adapted him.

In 1834 he again visited England, to attend the meeting of the British Association at Edinburgh. From this time till 1848 he led a life of comparative quiet--not the quiet of inactivity, however, for his incessant labours within the Academy and the Observatory produced a multitude of contributions to all departments of physical science,--but on the fall of Louis Philippe he left his laboratory to join in forming the provisional government. He was entrusted with the discharge of two important functions, that had never before been united in one person, viz. the ministry of war and of marine; and in the latter capacity he effected some salutary reforms, such as the improvement of rations in the navy and the abolition of flogging. He also abolished political oaths of all kinds, and, against an array of moneyed interests, succeeded in procuring the abolition of negro slavery in the French colonies.

In the beginning of May 1852, when the government of Louis Napoleon required an oath of allegiance from all its functionaries, Arago peremptorily refused, and sent in his resignation of his post as astronomer at the Bureau des Longitudes. This, however, the prince president, to his credit, declined to accept, and made "an exception in favour of a _savant_ whose works had thrown lustre on France, and whose existence his government would regret to embitter." But the tenure of office thus granted did not prove of long duration. Arago was now on his death-bed, under a complication of diseases, induced, no doubt, by the hardships and labours of his earlier years. In the summer of 1853 he was advised by his physicians to try the effect of his native air, and he accordingly set out for the eastern Pyrenees. But the change was unavailing, and after a lingering illness, in which he suffered first from diabetes, then from Bright's disease, complicated by dropsy, he died in Paris on the 2nd of October 1853.

Arago's fame as an experimenter and discoverer rests mainly on his contributions to magnetism and still more to optics. He found that a magnetic needle, made to oscillate over nonferruginous surfaces, such as water, glass, copper, &c., falls more rapidly in the extent of its oscillations according as it is more or less approached to the surface. This discovery, which gained him the Copley medal of the Royal Society in 1825, was followed by another, that a rotating plate of copper tends to communicate its motion to a magnetic needle suspended over it ("magnetism of rotation"). Arago is also fairly entitled to be regarded as having proved the long-suspected connexion between the aurora borealis and the variations of the magnetic elements.

In optics we owe to him not only important optical discoveries of his own, but the credit of stimulating the genius of A.J. Fresnel, with whose history, as well as with that of E.L. Malus and of Thomas Young, this part of his life is closely interwoven. Shortly after the beginning of the 19th century the labours of these three philosophers were shaping the modern doctrine of the undulatory theory of light. Fresnel's arguments in favour of that theory found little favour with Laplace, Poisson and Biot, the champions of the emission theory; but they were ardently espoused by Humboldt and by Arago, who had been appointed by the Academy to report on the paper. This was the foundation of an intimate friendship between Arago and Fresnel, and of a determination to carry on together further researches in this subject, which led to the enunciation of the fundamental laws of the polarization of light known by their names (see POLARIZATION). As a result of this work Arago constructed a _polariscope_, which he used for some interesting observations on the polarization of the light of the sky. To him is also due the discovery of the power of _rotatory polarization_ exhibited by quartz, and last of all, among his many contributions to the support of the undulatory hypothesis, comes the _experimentum crucis_ which he proposed to carry out for comparing directly the velocity of light in air and in water or glass. On the emission theory the velocity should be accelerated by an increase of density in the medium; on the wave theory, it should be retarded. In 1838 he communicated to the Academy the details of his apparatus, which utilized the revolving mirrors employed by Sir C. Wheatstone in 1835 for measuring the velocity of the electric discharge; but owing to the great care required in the carrying out of the project, and to the interruption to his labours caused by the revolution of 1848, it was the spring of 1850 before he was ready to put his idea to the test; and then his eyesight suddenly gave way. Before his death, however, the retardation of light in denser media was demonstrated by the experiments of H.L. Fizeau and J.B.L. Foucault, which, with improvements in detail, were based on the plan proposed by him.

Arago's _OEuvres_ were published after his death under the direction
of J.A. Barral, in 17 vols., 8vo, 1854-1862; also separately his
_Astronomie populaire_, in 4 vols.; _Notices biographiques_, in 3
vols.; _Notices scientifiques_, in 5 vols.; _Voyages scientifiques_,
in 1 vol.; _Memoires scientifiques_, in 2 vols.; _Melanges_, in 1
vol.; and _Tables analytiques et documents importants_ (with
portrait), in 1 vol. English translations of the following portions of
his works have appeared:--_Treatise on Comets_, by C. Gold, C.B.
(London, 1833); also translated by Smyth and Grant (London, 1861);
_Hist. eloge of James Watt_, by James Muirhead (London, 1839); also
translated, with notes, by Lord Brougham; _Popular Lectures on
Astronomy_, by Walter Kelly and Rev. L. Tomlinson (London, 1854); also
translated by Dr W.H. Smyth and Prof. R. Grant, 2 vols. (London,
1855); _Arago's Autobiography_, translated by the Rev. Baden Powell
(London, 1855, 1858); _Arago's Meteorological Essays_, with
introduction by Humboldt, translated under the superintendence of
Colonel Sabine (London, 1855), and _Arago's Biographies of Scientific
Men_, translated by Smyth, Powell and Grant, 8vo (London, 1857).

ARAGON, or ARRAGON (in Span. _Aragon_), a captaincy-general, and formerly a kingdom of Spain; bounded on the N. by the Pyrenees, which separate it from France, on the E. by Catalonia and Valencia, S. by Valencia, and W. by the two Castiles and Navarre. Pop. (1900) 912,711; area, 18,294 sq. m. Aragon was divided in 1833 into the provinces of Huesca, Teruel and Saragossa; an account of its modern condition is therefore given under these names, which have not, however, superseded the older designation in popular usage.

Aragon consists of a central plain, edged by mountain ranges. On the south, east and west, these ranges, though wild and rugged, are of no great elevation, but on the north the Pyrenees attain their greatest altitude in the peaks of Aneto (11,168 ft.) and Monte Perdido (10,998 ft.)--also known as Las Tres Sorores, and, in French, as Mont Perdu. The central pass over the Pyrenees is the Port de Canfranc, on the line between Saragossa and Pau. Aragon is divided by the river Ebro (q.v.), which flows through it in a south-easterly direction, into two nearly equal parts, known as Trans-ibero and Cis-ibero. The Ebro is the principal river, and receives from the north, in its passage through the province, the Arba, the Gallego and the united waters of the Cinca, Esera, Noguera Ribagorzana, Noguera Pallaresa and Segre--the last three belonging to Catalonia. From the south it receives the Jalon and Jiloca (or _Xalon_ and _Xiloca_) and the Guadalope. The Imperial Canal of Aragon, which was begun by the emperor Charles V. in 1529, but remained unfinished for nearly two hundred years, extends from Tudela to El Burgo de Ebro, a distance of 80 m.; it has a depth of 9 ft., and an average breadth of 69, and is navigable for vessels of about 80 tons. The Royal Canal of Tauste, which lies along the north side of the Ebro, was cut for purposes of irrigation, and gives fertility to the district. Two leagues north-north-east of Albarracin is the remarkable fountain called Cella, 3700 ft. above the sea, which forms the source of the Jiloca; and between this river and the Sierra Molina is an extensive lake called Gallocanta, covering about 6000 acres. The climate is characterized by extreme heat in the summer and cold in the winter; among the mountains the snowfall is heavy, and thunderstorms are frequent, but there is comparatively little rain.

Within a recent geological period, central Aragon was undoubtedly submerged by the sea, and the parched chalky soil remains saturated with salt, while many of the smaller streams run brackish. As the mountains of Valencia and Catalonia effectually bar out the fertilizing moisture of the sea-winds, much of the province is a sheer wilderness, stony, ash-coloured, scarred with dry watercourses, and destitute of any vegetation except thin grass and heaths. In contrast with the splendid fertility of Valencia or the south of France, the landscape of this region, like the rest of central Spain, seems almost a continuation of the north African desert area. There are, however, extensive oak, pine and beech forests in the highlands, and many beautiful oases in the deeply sunk valleys, and along the rivers, especially beside the Ebro, which is, therefore, often called the "Nile of Aragon." In such oases the flora is exceedingly rich. Wheat, maize, rice, oil, flax and hemp, of fine quality, are grown in considerable quantities; as well as saffron, madder, liquorice, sumach, and a variety of fruits. Merino wool is one of the chief products.

In purity of race the Aragonese are probably equal to the Castilians, to whom, rather than to the Catalans or Valencians, they are also allied in character. The dress of the women is less distinctive than that of the men, who wear a picturesque black and white costume, with knee-breeches, a brilliantly coloured sash, black hempen sandals, and a handkerchief wound round the head.

Three counties--Sobrarbe, situated near the headwaters of the Cinca, Aragon, to the west, and Ribagorza or Ribagorca, to the east--are indicated by tradition and the earliest chronicles as the cradle of the Aragonese monarchy. These districts were never wholly subdued when the Moors overran the country (711-713). Sobrarbe especially was for a time the headquarters of the Christian defence in eastern Spain. About 1035, Sancho III. the Great, ruler of the newly established kingdom of Navarre, which included the three counties above mentioned, bequeathed them to Gonzalez and Ramiro, his sons. Ramiro soon rid himself of his rival, and welded Sobrarbe, Ribagorza and Aragon into a single kingdom, which thenceforward grew rapidly in size and power and shared with Castile the chief part in the struggle against the Moors. The history of this period, which was terminated by the union of Castile and Aragon under Ferdinand and Isabella in 1479, is given, along with a full account of the very interesting constitution of Aragon, under SPAIN (q.v.). At the height of its power under James I. (1213-1276), the kingdom included Valencia, Catalonia, the Balearic Islands and the considerable territory of Montpellier in France; while Peter III. (1276-1285) added Sicily to his dominions.

The literature relating to Aragon is very extensive. See, in addition
to the works cited in the article SPAIN (section _History_), "Les
Archives d'Aragon et de Navarre," by L. Cadier, in _Bibliotheque de
l'Ecole des Chartes_, 49 (Paris, 1888). Among the more important
original authorities, the following may be selected:--for general
history, _Anales de la corona de Aragon_, by G. Curita, 3rd ed. in 7
folio volumes (Saragossa, 1668-1671; 1st ed. 1562-1580);--for
ecclesiastical history, _Teatro historico de las iglesias de Aragon_
(Pamplona, 1770-1807); for economic history, _Historia de la economia
politica de Aragon_, by I.J. de Asso y del Rio (Saragossa, 1798). For
the constitution and laws of Aragon, see _Origines del Justicia de
Aragon_, &c., by J. Ribera Tarrago (Saragossa, 1897), and
_Instituciones y reyes de Aragon_, by V. Balaguer (Madrid, 1896). The
topography, inhabitants, art, products, &c., of the kingdom are
described in a volume of the series _Espana_ entitled _Aragon_, by
J.M. Quadrado (Barcelona, 1886).

ARAGONITE, one of the mineral forms of calcium carbonate (CaCO3), the other form being the more common mineral calcite. It crystallizes in the orthorhombic system, and the crystals are either prismatic or acicular in habit. Simple crystals are, however, rare; twinning on the prism planes (_M_ in the figures) being a characteristic feature of the mineral (fig. 1). This twinning is usually often repeated on the same plane (fig. 2), and gives rise to striations on the terminal faces (k) of the crystals; often, also, three crystals are twinned together on two of the prism planes of one of them, producing an apparently hexagonal prism. The mineral is colourless, white or yellowish, transparent or translucent, has a vitreous lustre, and, in fact, is not unlike calcite in general appearance. It may, however, always be readily distinguished from calcite by the absence of any marked cleavage, and by its greater hardness (H. = 3-1/2-4) and specific gravity (2.93); further, it is optically biaxial, whilst calcite is uniaxial. It is brittle and has a subconchoidal fracture; on a fractured surface the lustre is decidedly resinous in character.

The mineral was first found, as reddish twinned crystals with the form of six-sided prisms, at Molina in Aragon, Spain, where it occurs with gypsum and small crystals of ferruginous quartz in a red clay. It is from this locality that the mineral takes its name, which was originally spelt arragonite. Fine groups of crystals of the same habit are found in the sulphur deposits of Girgenti in Sicily; also at Herrengrund near Neusohl in Hungary. At many other localities the mineral takes the form of radiating groups of acicular crystals, such as those from the haematite mines of west Cumberland: beautiful feathery forms have been found in a limestone cave in the Transvaal. Fibrous forms are also common. A peculiar coralloidal variety known as _flosferri_ ("flower of iron") consists of radially arranged fibres: magnificent snow-white specimens of this variety have long been known from the iron mines of Eisenetz in Styria. The calcareous secretions of many groups of invertebrate animals consist of aragonite (calcite is also common); pearls may be specially cited as an example.

Aragonite is a member of the isomorphous group of minerals comprising witherite (BaCO3), strontianite (SrCO3), cerussite (PbCO3) and bromlite ((Ba, Ca)CO3); and crystals of aragonite sometimes contain small amounts of strontium or lead. A variety known as tarnowitzite, from Tarnowitz in Silesia, contains about 5% of lead carbonate.

Aragonite is the more unstable of the two modifications of calcium carbonate. A crystal of aragonite when heated becomes converted into a granular aggregate of calcite individuals: altered crystals of this kind (paramorphs) are not infrequently met with in nature, whilst in fossil shells the original nacreous layer of aragonite has invariably been altered to calcite. From a solution of calcium carbonate in water containing carbon dioxide crystals of calcite are deposited at the ordinary temperature, but from a warm solution aragonite crystallizes out. The thermal springs of Carlsbad deposit spherical concretions of aragonite, forming masses known as pisolite or _Sprudelstein_. (L. J. S.)

ARAGUA, one of the smaller states of Venezuela under the redivision of 1904, lying principally within the parallel ranges of the Venezuelan Cordillera, and comprising some of the most fertile and healthful valleys of the republic. It is bounded E. by the Federal District and Maturin, S. by Guarico and W. by Zamora and Carabobo. Pop. (1905, est.) 152,364. Aragua has a short coast-line on the Caribbean west of the Federal District, but has no port of consequence. Cattle, swine and goats are raised, and the state produces coffee, sugar, cacao, beans, cereals and cheese. The climate of the higher valleys is subtropical, the mean annual temperature ranging from 74 deg. to 80 deg. F. The capital, La Victoria (pop. 7800), is situated in the fertile Aragua valley, 1558 ft. above sea-level and 36 m. south-west of Caracas. Other important towns are Barbacoas (pop. 13,109) on the left bank of the Guarico in a highly fertile region, Ciudad de Cura and Maracay (pop. 7500), 56 m. west-south-west of Caracas near the north-east shore of Lake Valencia. The last two towns are on the railway between Caracas and Valencia.

ARAGUAYA, ARAGUAY or ARAGUIA, a river of Brazil and principal affluent of the Tocantins, rising in the Serra do Cayapo, where it is known as the Rio Grande, and flowing in a north by east direction to a junction with the Tocantins at Sao Joao do Araguaya, or Sao Joao das Duas Barras. Its upper course forms the boundary line between Goyaz and Matto Grosso. The river divides into two branches at about 13 deg. 20' S. lat., and unites again at 10 deg. 30', forming the large island of Santa Anna or Bananal. The eastern branch, called the Furo, is the one used by boats, as the main channel is obstructed by rapids. Its principal affluent is the Rio das Mortes, which rises in the Serra de Sao Jeronymo, near Cuyaba, Matto Grosso, and is utilized by boatmen going to Para. Of other affluents, the Bonito, Garcas, Cristallino and Tapirape on the west, and the Pitombas, Claro, Vermelho, Tucupa and Chavante on the east, nothing definite is known as the country is still largely unexplored. The Araguaya has a course of 1080 m., considerable stretches of which are navigable for small river steamers, but as the river below Santa Anna Island is interrupted by reefs and rapids in two places--one having a fall of 85 ft. in 18 m., and the other a fall of 50 ft. in 12 m.--it affords no practicable outlet for the products of the state. It was explored in part by Henri Coudreau in 1897.

See Coudreau's _Voyage au Tocantins-Araguaya_ (Paris, 1897).

ARAKAN, a division of Lower Burma. It consists of a strip of country running along the eastern seaboard of the Bay of Bengal, from the Naaf estuary, on the borders of Chittagong, to Cape Negrais. Length from northern extremity to Cape Negrais, about 400 m.; greatest breadth in the northern part, 90 m., gradually diminishing towards the south, as it is hemmed in by the Arakan Yoma mountains, until, in the extreme south, it tapers away to a narrow strip not more than 15 m. across. The coast is studded with islands, the most important of which are Cheduba, Ramree and Shahpura. The division has its headquarters at Akyab and consists of four districts--namely, Akyab, Northern Arakan Hill Tracts, Sandoway and Kyaukpyu, formerly called Ramree. Its area is 18,540 sq. m. The population at the time of the British occupation in 1826 did not exceed 100,000. In 1831 it amounted to 173,000; in 1839 to 248,000, and in 1901 to 762,102.

The principal rivers of Arakan are--(1) the Naaf estuary, in the north, which forms the boundary between the division and Chittagong; (2) the Myu river, an arm of the sea, running a course almost parallel with the coast for about 50 m.; (3) the Koladaing river, rising near the Blue mountain, in the extreme north-east, and falling into the Bay of Bengal a few miles south of the Myu river, navigable by vessels of from 300 to 400 tons burden for a distance of 40 m. inland; and (4) the Lemyu river, a considerable stream falling into the bay a few miles south of the Koladaing. Farther to the south, owing to the nearness of the range which bounds Arakan on the east, the rivers are of but little importance. These are the Talak and the Aeng, navigable by boats; and the Sandoway, the Taungup and the Gwa streams, the latter of which alone has any importance, owing to its mouth forming a good port of call or haven for vessels of from 9 to 10 ft. draught. There are several passes over the Yoma mountains, the easiest being that called the Aeng route, leading from the village of that name into Upper Burma. The staple crop of the province is rice, along with cotton, tobacco, sugar, hemp and indigo. The forests produce abundance of excellent oak and teak timber.

The natives of Arakan trace their history as far back as 2666 B.C., and give a lineal succession of 227 native princes down to modern times. According to them, their empire had at one period far wider limits, and extended over Ava, part of China, and a portion of Bengal. This extension of their empire is not, however, corroborated by known facts in history. At different times the Moguls and Pegus carried their arms into the heart of the country. The Portuguese, during the era of their greatness in Asia, gained a temporary establishment in Arakan; but in 1782 the province was finally conquered by the Burmese, from which period until its cession to the British in 1826, under the treaty of Yandaboo, its history forms part of that of Burma. The old city of Arakan, formerly the capital of the province, is situated on an inferior branch of the Koladaing river. Its remoteness from the ports and harbours of the country, combined with the extreme unhealthiness of its situation, have led to its gradual decay subsequently to the formation of the comparatively recent settlement of Akyab, which place is now the chief town of the province. The old city (now Myohaung) lies 50 m. north-east of Akyab. The Maghs, who form nearly the whole population of the province, follow the Buddhist doctrines, which are universally professed throughout Burma. The priests are selected from all classes of men, and one of their chief employments is the education of children. Instruction is consequently widely diffused, and few persons, it is said, can be found in the province who are unable to read. The qualifications for entering into the priestly order are good conduct and a fair measure of learning--such conduct at least as is good according to Buddhist tenets, and such learning as is esteemed among their votaries.

The Arakanese are of Burmese origin, but separated from the parent stock by the Arakan Yoma mountains, and they have a dialect and customs of their own. Though conquered by the Burmese, they have remained distinct from their conquerors.

The Northern Arakan Hill Tracts district is under a superintendent, who is usually a police officer, with headquarters at Paletwa. The area of the Hill Tracts is 5233 sq. m.; pop. (1901) 20,682. (J. G. Sc.)