Chapter XXIV: Appendix: “Rhizopods in Poliomyelitis acuta.” (18)

Males are oval in shape, 0·12 mm. in length and 0·08 mm. in breadth, flattened. There are six pairs of chitinous hairs on the dorsal surface and a lyre-shaped lamella on the posterior part. The female in the non-gravid state is cylindrical in form, 0·2 mm. in length and 0·07 mm. in breadth; when gravid the posterior part of the body becomes enlarged into a ball, which may attain 1·5 mm. in size, as in the case of _Pulex penetrans_ and of the female Termites. On emerging the young are already provided with four pairs of legs and copulate soon after birth.

These animals live on the stalks of cereals, and feed on vegetable
and animal juices; they are also found on corn-infesting insects.
They invade the barns and seek out the insects living in the dry
grains of corn, or wait for an opportunity of obtaining food. They
have been repeatedly observed on human beings, particularly labourers
occupied in handling grain; their bite causes severe irritation,
local elevation and reddening of the epidermis, as well as fever. It
cannot be positively asserted that all cases of the occurrence of
cereal mites on man relate to _P. ventricosus_, as the descriptions
are often insufficient. Geber states that one form is _Chrithoptes
monunguiculosus_, or _Acarus hordei_; Flemming mentions _Tarsonemus
uncinatus_; Koller _Oribates_ sp.; and Karpelles _Tarsonemus
intectus_.

[The pregnant female Pediculoides has a large round inflated abdomen,
in which the ova hatch and the young mature. Later they escape from
the parent as adults.--F. V. T.]

Genus. *Nephrophages.*

*Nephrophages sanguinarius*, Miyake and Scriba, 1893.

Males measure 0·117 mm. in length and 0·079 mm. in breadth; females up to 0·360 mm. in length by 0·120 mm. in breadth. The head is provided with two very large scissors-like jaws and two large round eyes. The legs are composed of five segments and are all of equal length; the three anterior pairs of legs have pedunculated ambulacra, the posterior ones terminate in a claw. The cuticle on the back is thickened in three places, shield-like; the abdominal surface without scutellum is longitudinally striped and is beset with chitinous hairs. Colour greenish to brownish-yellow. Eggs 0·046 to 0·040 mm.

The authors discovered these mites, but always dead, in the urine
of a Japanese suffering from fibrinuria complicated with chyluria
and hæmaturia. They surmised that they were endoparasites, probably
situated in the kidney; but this view is not convincing, though they
also report that for a week, day after day, the mites were found in
the patient’s urine, as well as in urine drawn off by means of a
catheter, and in the water used to wash out the bladder (one or two
specimens and an egg). The statement that these mites have large eyes
makes the discovery suspicious, to say the least. The significance of
the discovery is not supported by the further statement that Disse
is supposed to have found an encapsuled mite closely related to the
Tyroglyphides on the wall of the vena cava.

In the case of Marpmann, who found a dead Acarid in the urine of a
man suffering from chronic nephritis, and in whom later examinations
proved negative, the author himself was of opinion that the mite had
reached the urine from outside.

We are certainly acquainted with mites living endoparasitically,
namely, the _Cysticolæ_, _Analgesinæ_, of which _Laminosioptes
gallinarum_ live in the intramuscular and subcutaneous connective
tissue of fowls, and _Cytoleichus sarcoptoïdes_ in their air sacs.
Another kind of mite (_Halarachne halichœri_) is occasionally found
in the nasal mucous membrane of the seal (_Halichœrus grypus_), and,
quite recently, _Pneumonyssus simicola_, which is more nearly related
to Halarachne, has been found in the lung of _Cynocephalus_ sp. It is
therefore not improbable that endoparasitic mites are found in man;
but no definite discovery has yet been made.

Family. *Eupodidæ.*

Small tracheate mites, with moderately long or short pedipalpi,
composed of four segments, of which the last segments bend; cheliceræ
forceps-shaped, with serrated edges; legs with two claws, more rarely
with one, and terminating in a tuft ornamented with fine hairs;
genital orifices on the abdomen, surrounded by a circle of little
hairs. Most species live free--one lives parasitically on the bodies
of slugs.

Genus. *Tydeus*, Koch.

*Tydeus molestus*, Moniez, 1889.

Male, 0·2 mm. in length, 0·125 mm. in breadth. Females, 0·225 mm. in length, 0·135 mm. in breadth; gravid female 0·315 to 0·360 mm. in length and 0·180 mm. in breadth. They were observed by Moniez on an estate in Belgium, whither the creature had apparently been imported twenty-five years previously with Peruvian guano; they appeared regularly in the summer and remained until the first frost set in; they were found on grass-plots, on trees and bushes in masses; they regularly attacked human beings, mammals and birds, tormenting their hosts in a terrible manner.

Family. *Gamasidæ* (Coleopterous or Insect Mites).

Cheliceræ chelate or styliform; pedipalpi filiform; the legs are
composed of six segments with two terminal ungues and a bladder-like
sucking disc [caruncle--F. V. T.]. Stigmata situated between the
third and fourth pairs of legs; the cuticle thickened, leather-like;
no eyes; the larvæ have six legs.

The _Gamasidæ_ are predaceous on small insects and other mites; some
are parasitic on insects, and one is noticeable as a pest on birds,
etc.

Genus. *Dermanyssus*, Dugés.

*Dermanyssus gallinæ*, de Geer, 1778.

Syn.: _Pulex gallinæ_, Redi, 1674; _Atarus gallinæ_, de Geer, 1778;
_Dermanyssus avium_, Dugés, 1834.

The male measures 0·6 mm. in length by 0·32 mm. in breadth; the female 0·7 to 0·75 mm. in length by 0·4 mm. in breadth. The body is somewhat pear-shaped; the colour whitish, reddish, or reddish-black, according to the contents of the intestine. The legs are fairly short and strong. During the day they live concealed in the nests, cracks, etc., of the hen-house, and at night attack the inmates in order to suck their blood; they rarely remain long on the birds. They have been repeatedly found on persons, on whose skin they produce an itching eruption.

*Dermanyssus hirundinis*, Hermann, 1804.

Syn.: _Acarus hirundinis_, Herm., 1804.

Of a brownish colour, 1·2 or 1·4 mm. in length; lives in the nests of swallows and is occasionally found on man.

[The red hen mite (_Dermanyssus gallinæ_) not only attacks poultry and man, as stated above, but is found on all birds and many mammals. The _D. gallinæ_ is the same as _D. avium_. The species found in swallows’ nests is also said to be the same. This mite can remain for weeks without any food from its normal host. They only attack man when entering or cleaning dirty and neglected fowl-houses; they do not produce a true dermatosis. They chiefly attack the backs of the hands and forearms of those who constantly attend poultry and give rise to symptoms similar to the papular eczema of scabies. That they may remain some time upon the human body we know from the following cases out of many recorded: Geber observed that the Dermanyssus had caused a diffused eczema on a woman, which lasted four weeks and then disappeared. The _tique_ of F. V. Raspail is the bird Dermanyssus; he records children and adults being attacked not only when handling pigeons, but even when walking in a garden manured with pigeons’ dung. The affection soon disappeared when the pigeons were destroyed and the excreta buried. I have frequently heard of poultrymen being seriously attacked by this pest.--F. V. T.]

Genus. *Holothyrus.*

*Holothyrus coccinella*, Gervais, 1842.

Measures 5 mm. in size; lives on birds in the Island of Mauritius; ducks and geese frequently fall victims to its bite; it also attacks human beings, on whose skin it causes severe burning and swelling, but no reddening; it may be dangerous to children, especially by settling in the oral cavity.

Other Gamasides occasionally occur in man, for instance, according
to Moniez, _Leignathus sylviarum_, Canestr. et Fanzago; according to
Neumann _Lælaps stabularis_. The former live normally in the nests of
various species of _Sylvia_, Lælaps on dried vegetable substances,
also in houses.

[Marchoux and Conoy (_Bull. Soc. Path. exot._, 1912, v, No. 10, pp. 796–798) found Leishman granules in _Lælaps echidninus_. It is assumed that Leishman granules may be found in most Arachnoids, and have no connection with Spirochæta.--F. V. T.]

Family. *Ixodidæ* (Ticks).

Comparatively large Acarines with a leathery skin; they are flattened
in form, but after sucking blood the abdomen becomes spherical;
the cheliceræ are rod-like and possess a serrated terminal joint,
bent hook-like; the median parts of the pedipalpi (maxillæ) form a
rostrum furnished with barbed hooks (fig. 359); the maxillary palpi
themselves are club-like or rounded; the legs are composed of six
segments with two terminal ungues, often also with “sucking discs”;
the stigmata are at the sides of the body, posterior to the fourth or
third pair of legs. The larvæ are six-legged.

[The true ticks (_Ixodidæ_) are all blood-suckers, and as far as is known they do not take vegetable food at all. Not only are the _Ixodidæ_ important as actual parasites, but they are most so on account of the fact that they are the active agents in carrying various diseases in animals and apparently in man. It has been conclusively proved that the bont tick (_Amblyomma hebræum_) is the carrier of the fatal “heart-water fever” so rife amongst sheep in South Africa, that the dog tick (_Hæmaphysalis leachi_) is the agent by which the protozoa that cause malignant jaundice in dogs are distributed, that Texas fever in cattle is spread by _Rhipicephalus annulatus_, and Coast or Rhodesian fever by _R. appendiculatus_ and _R. simus_. Their importance as disease carriers amongst mammals is therefore considerable, and it may prove to be so for man.[336] They frequently attack man, but chiefly, according to my observations, in their early stages in Europe; this is not so, however, abroad. The life-history of a number of ticks has been clearly demonstrated. Mr. Wheler has shown that in _Ixodes reduvius_ it is as follows: the female deposits her eggs in masses upon the ground, gradually reducing in size as the eggs pass out, until she finally remains a mere shrivelled empty bag and then dies. The eggs are oval, golden brown in colour and smooth; in length they are 0·59 mm.; as in all _Ixodidæ_ they are covered with a glutinous secretion, by means of which they adhere together in masses. These egg masses may be deposited anywhere on the ground, but amongst rough, coarse herbage seems to be the favourite place. The egg stage may last as long as twenty-two weeks, or it may only take eight weeks. In the case of the bont tick a single female may deposit 15,000 or more eggs. The process of egg-laying is described as follows by Mr. Wheler: “When egg-laying is about to take place, the head is further depressed till it rests close against the under side of the body. In this attitude the end of the rostrum actually touches the genital orifice, the palpi being at the same time widely opened out. Behind the head and from beneath the shield, at what for the purposes of explanation may be described as the back of the neck, a white, perfectly transparent, delicate gelatinous membrane is brought down through inflation, either with air or with a transparent fluid, above the head, which it temporarily conceals. The end of this membrane terminates in two conical points which appear to be covered with a glutinous secretion, and at the same time an ovipositor of a somewhat similar character, but only semi-transparent, is pushed forward from the genital orifice. This latter is a tube, within which is the egg. As the ovipositor projects it turns itself inside out, like the finger of a glove, leaving the egg protruded at the end and lying between the two finger-like points of the membrane. The membrane and the ovipositor are then withdrawn each from the other. The egg adheres to the former, which collapses through the withdrawal of its contents, dragging the head forward and depositing it on the top of the head. Neither legs, palpi, nor the organs of the mouth take any part in oviposition, but after the collapse of the membrane the palpi are closed and the head is raised, by which action the egg is pushed forward to the front edge of the shield, forming in time an adherent mass of eggs, which are deposited in front of the tick.”

[336] This has been proved in Uganda--so-called tick fever in man.

[The egg gives rise to the larval form, the so-called “seed-tick” stage. At first these minute specks are pallid and soft, but they soon harden and darken in colour. These larvæ are six-legged and crawl up grasses and various plants, and there await a passing host, waving their two front legs in the air and becoming attached by this means. The larval ticks feed upon the blood of the host, and when replete fall to the ground, the body becoming inflated in the meanwhile. These larvæ may remain on the host only two days, or they may remain much longer. Eventually they moult on the ground and change to the nymph or pupal stage, which has four pairs of legs. This pupa acts just as the larva, crawls up plants and waits to regain the host. After a time the nymphs, having gorged themselves with blood, fall off and remain on the ground for nearly three months; they then moult and become adult males and females. In about ten days they assume their normal colour and regain the host afresh; the female gradually swells until she attains that large inflated form so characteristic of ticks. The male does not swell, but nevertheless feeds upon the host and fertilizes the female.

[The act of coitus is strange: the male tick inserts its rostrum and other mouth organs into the sexual orifice of the female, between the base of the posterior pair of legs. The males then die and the females fall to the ground and deposit the ova. There are variations in the different species, of course, from those given above, which apply solely to _Ixodes reduvius_. The larvæ and nymphs seem to attack most animals, but the adults mainly keep to the same host. The periods in the life-cycle of ticks not only vary in the different species, but in each species according to climatic conditions; for instance, in the bont tick (_Amblyomma hebræum_, Koch), Lounsbury has shown that the development is rapid in summer, slow in winter. The period from the time that the female drops to the time she commences to lay eggs varied in specimens observed by him from twelve days in summer to twelve weeks in winter, and the complete period from the dropping of the female to the hatching of the eggs, from eleven weeks in summer to thirty-six weeks through the winter. Other stages vary in a similar manner.

[Ticks may live a long time away from the host provided they are supplied with a certain amount of moisture. Mr. Wheler kept dog ticks (_Ixodes plumbeus_) in the larval stage for ten months; the pupæ, male and female, of _I. reduvius_ for six months.

[I have kept _Ornithodorus moubata_ alive for eighteen months without food.

[In many species moulting takes place off the host, but in _I. bovis_, now known as _Rhipicephalus annulatus_, Say (the carrier of Texas fever), moulting takes place on the host, and in many other species also.[337] Some species of ticks leave their host on its death (as the dog tick, _Hæmaphysalis leachi_), but others die with the host (bont tick, _Amblyomma hebræum_).

[337] Some ticks require only one (_R. decoloratus_), others two (_R. evertsi_), and some three hosts (_R. appendiculatus_) in order to reach maturity.

[Two species are of special importance, namely _Ornithodorus moubata_, Murray, which may infect human beings with the spirillum of African tick fever, and _Dermatocentor reticulatus_ var. _occidentalis_, which is said to be the carrier of Rocky Mountain spotted fever.

CLASSIFICATION OF _Ixodidæ_.

[The ticks, or _Ixodidæ_, are divided into two groups, known as (1) _Argantinæ_, (2) _Ixodinæ_. The _Argantinæ_ are told from the _Ixodinæ_ by the absence of dorsal or ventral shields in both sexes, and also by the rostrum being placed beneath the cephalothorax, which covers it over: except in the larval stage, in which it is subterminal, and in the pupal, when it partly projects. Legs nearly equal in length. The sexual orifice is situated between the two first pairs of legs. The males usually smaller than the females.

[The _Ixodinæ_ have the legs unequal, of six segments with two false segments, making them look as if composed of eight segments. The rostrum is terminal and never hidden beneath the body. The sexual orifice is situated between the bases of the first three pairs of legs. In the males the orifice is obsolete or very rudimentary, sexual intercourse being effected by the rostrum. The males are smaller than the females. The shield in the females never covers so much as one-half of the body even when fasting, also in the larvæ and nymphs; but in the males, which do not distend, the shield covers the body entirely, or all but a narrow margin. The _Ixodinæ_ are divided into two groups: (i) the _Ixodæ_, and (ii) the _Rhipicephalæ_. The former have a long proboscis reaching nearly to the end of the palpi or even a little longer than the palpi. The palpi are longer than broad. The _Rhipicephalæ_ have short palpi, nearly or quite as broad as long, more or less conical or subtriangular. They were called _Conipalpi_ by Canestrini.

SYNOPSIS OF GENERA.

[A. _Argantinæ_: Rostrum concealed in adult, partly
exposed in larvæ and nymphs. No dorsal and
ventral shields.
Body flat with thin edges, finely shagreened and
punctate _Argas_.
Body with numerous small round granules and with
thick sides _Ornithodorus_.

[B. _Ixodinæ_: Rostrum terminal. Body with dorsal
shield over some part of it.

I. Rostrum and palpi longer than broad (_Ixodæ_).
α. A groove around anus in front.
Palpi caniculated in both sexes _Ixodes_.
Palpi claviform, not caniculated in the
male; legs very long _Eschatocephalus_.
Palpi claviform, not caniculated in the
male; _anal groove absent in the female_ _Ceratixodes_.
β. A groove around the anus behind.
No eyes; adanal shields _Aponomma_.
Eyes present.
Males with no adanal shields _Amblyomma_.
Males with adanal shields _Hyalomma_.
II. Labium and palpi short; palpi not, or very
little, longer than broad (_Rhipicephalæ_).
α. No eyes.
Rostrum rectangular; no ventral shields in
the male _Hæmaphysalis_.
β. Eyes present.
No adanal shields, but usually with greatly
developed coxæ on fourth pair of legs.
Capitulum quadrangular _Dermacentor_.
Capitulum hexagonal _Rhipicentor_.
Adanal shields in male. Stigmata comma-
shaped _Rhipicephalus_.
Stigmata oval or round; legs normal _Boophilus_.
Segments of legs expanded _Margaropus_.

[The genus Ceratixodes of Neumann, 1902, occurs on birds.
[The genus Eschatocephalus of Frauenfeld, 1853, of which seven
species are known, is mostly parasitic on bats, and is found
in holes, caves, and church towers.
[The genus Aponomma of Neumann, 1899, is exotic, and almost
entirely confined to snakes and saurians.
[The following are synonyms of the different genera:--
_Argas_, Latreille, 1796 (_Rhynchoprion_, Hermann, 1804).
_Ixodes_, Latreille, 1795 (_Acarus_, Linnæus, 1758;
_Cynorhæstes_, Hermann, 1804; _Crotonus_, Dumeril, 1822).
_Ceratixodes_, Neumann, 1902 (_Ixodes_, Cambridge, 1879;
_Hyalomma_, Cambridge, 1879).
_Eschatocephalus_, Frauenfeld, 1853 (_Sarconyssus_, Kolenati,
1857).
_Amblyomma_, Koch, 1844 (_Ixodes_, Latreille, 1795).
_Hæmaphysalis_, Koch, 1844 (_Rhipistoma_, Koch, 1844;
_Gonixodes_, Dugès, 1888; _Opitodon_, Canestrini, 1897).
_Rhipicephalus_, Koch, 1844 (_Acarus_, Linnæus, 1758;
_Ixodes_, Latreille, 1795; _Phanloixodes_, Berlese, 1889;
_Boophilus_, Curtice, 1890).
_Dermacentor_, Koch, 1844 (_Ixodes_, Latreille, 1795;
_Pseudixodes_, Haller, 1882).--F. V. T.]

Genus. *Ixodes*, Latreille.

*Ixodes reduvius*, L., 1758.[338]

[338] _Ixodes reduvius_ and _I. ricinus_ are synonymous. [The above should read _Ixodes ricinus_, Latreille, 1806.--F. V. T.]

Syn.: _Acarus reduvius_ and _ricinus_, L.; _Ixodes ricinus_,
Latreille, 1806.

The males are oval; their length 1·2 to 2 mm.; they are brownish-red or black in colour; the females are yellowish-red, 4 mm. long; when gorged they are lead-coloured, and may attain 12 mm. in length by 6 to 7 mm. in breadth.

The dog tick (fig. 360) lives in thickets on leaves, etc., and
attacks sheep and oxen, and more rarely dogs, horses, and human
beings, into the skin of which the female bores with the rostrum in
order to suck blood; the bite is not dangerous, and sometimes is
not even felt. Inflammation, however, is set up if the creatures
are forcibly removed from the wound, as the rostrum as a rule
is torn off in the process. If left alone or smeared over with
some grease--vaseline, oil, butter, etc.--the creatures drop off
spontaneously. Sometimes the entire tick bores itself into the skin;
they also appear to be permanent inmates of kennels.

[The species _I. reduvius_ is the same as _I. ricinus_, Latreille. The male is 2·35 to 2·80 mm. long; the body is dark brown, almost black, with a pale, almost white, margin; there are also traces of reddish mottling. Coxæ of the first pair of legs with a short spine. Rostrum much shorter than that of the female; shield oval; anal shield small, about one-third the length of ventral shield. The adult female varies from 2·80 to 3·5 mm. when not distended, but when gorged may reach 10 mm. long. The shield and legs are dark blackish-brown, body deep orange-red with four dark longitudinal lines, paler beneath and light grey in front. When distending it is pale red to grey or white; when fully gorged olive-green, or dark red to black, with irregular yellow streaks on the back and sides just before egg-laying. Sexual orifice opposite fourth pair of legs. The nymph varies from 1·60 to 1·70 mm. long when fasting; the body is olive-white, opaque, with four distinct brown posterior markings and similar anterior ones, leaving a pale centre to the shield. When fully gorged it is 3 mm. long. As the nymph distends, it changes from opaque white to blue-black, and finally black. The little larva is 0·80 to 1·50 mm. long, transparent with olive-green intestinal markings; as it becomes inflated it changes to blue-black, and then black. There are no eyes. It is widely distributed, and chiefly attacks sheep; sometimes it occurs on dogs and also attacks man. Mégnin records it from horses in the nymph stage. Amongst its other numerous hosts are goats, cattle, deer, hedgehogs, moles, bats, birds, and lizards. It is usually known as the grass tick and bottle-nosed tick. This species occurs in Europe, Asia, North Africa, and North America.

[_Synonyms._--Considerable confusion exists over the name of this and other common ticks, owing to the same species having been described under a great many names. Observers have taken the same species on different animals and in various stages to be distinct, and have described them accordingly.

[The name _Ixodes reduvius_, Leach, does not stand, as Leach was describing quite a different parasite. The name _I. ricinus_, Latreille, 1806, is now substituted by Neumann and Wheler.

[The synonyms given by Wheler are as follow: _Reduvius_, Charleton, 1668; _Ricinus caninus_, Ray, 1710; _Acarus ricinoides_, de Geer, 1778; _Acarus ricinus_, Linnæus, 1788; _Cynorhæstes reduvius_, Hermann, 1804; _Cynorhæstes ricinus_, Hermann, 1804; _Ixodes megathyreus_, Leach, 1815; _Ixodes bipunctatus_, Risso, 1826; _Cynorhæstes hermanni_, Risso, 1826; _Crotonus ricinus_, Dumeril, 1829; _Ixodes trabeatus_, Audouin, 1832; _Ixodes plumbeus_, Dugés, 1834; _Ixodes reduvius_, Hahn, 1834; _Ixodes fuscus_, Koch, 1835 (?); _Ixodes lacertæ_, Koch, 1835 (?); _Ixodes pustularum_, Lucas, 1866; _Ixodes fodiens_, Murray, 1877; _Ixodes rufus_, _Ixodes sulcatus_, and _Ixodes sciuri_, Koch.--F. V. T.]

*Ixodes holocyclus*, Neumann, 1899.

[Under the name _I. holocyclus_, Cleland (_Journ. Trop. Med. and Hyg._, 1913, xvi, No. 3, pp. 43–45) says that: “This tick is common in man where there is dense scrub and tropical jungle along the east coast of Australia at certain times of the year. It may cause severe symptoms in children resulting in death.” He records a child being attacked in 1884 which died, and another case from which 200 ticks were removed, the symptoms being weak heart, collapse, syncope, but the patient recovered under treatment; again, in the same journal (pp. 188, 189), the case of a 4-1/2-year-old girl who was bitten showed widespread muscular paralysis, and other cases resembling conium poison.

[Taylor (_Rep. Ent. Aust. Inst. Trop. Med._, 1911, p. 21, 1913) refers to this species as the scrub tick of New South Wales. The partially fed female has a dark reddish-yellow scutum and is almost as broad as long, punctations very numerous, equal and confluent in places, long white hairs on the lower half of each coxa. He records it as attacking man commonly, mentioning Kamerunga, Cairns district, Queensland, and Sydney, N.S.W., as localities.--F. V. T.]

*Ixodes hexagonus*, Leach, 1815.

Syn.: _Ixodes sexpunctatus_, Koch, 1897; _I. vulpis_, Pagenstecher,
1861.

Lives in the same manner as the foregoing; especially attacks hounds, but also other mammals and even birds. The difference consists in the shape of the legs, the shorter rostrum, and the larger size of the male. It also occasionally attacks man, but is usually confused with the previously mentioned species.

[The synonyms of this species are as follow:[339] _Ixodes autumnalis_, Leach, 1815; _I. erinacei_, Audouin, 1832; _I. reduvius_, Audouin, 1832; _I. crenulatus_, Koch; _I. erinaceus_, Murray, 1877; _I. ricinus_, Mégnin, 1880.[339] Two other synonyms are given above by Braun.

[339] Neumann, G. L., “Rev. de la fam. des Ixodides,” _III Mém. Soc. Zool. France_, 1899, xii, p. 129.

[The female when fully replete is 11 mm. long, when fasting 3·86 mm.; the shield is heart-shaped and punctate, body finely hairy; palpi short and broad; labium shorter, and tarsi of all the legs more truncate than in _I. ricinus_. The colour of the distended body is drab and somewhat waxy; rostrum, shield and legs light testaceous. The male varies from 3·5 to 4·0 mm. long, and is reddish-brown in colour with lighter legs; the shield is punctate and leaves a narrow margin around the body; the body is elliptical, almost as large in front as behind. There is a spine on the coxæ of the first pair of legs, which is shorter than in the male _I. ricinus_ and longer than in the female. The genital orifice is opposite the interval between the second and third pair of legs. The fasting _nymph_ is 1·76 mm. long, light bluish-grey, margined and transparent, with four large posterior intestinal marks joined together behind the shield and smaller ones extending to the front and sides. When fully distended it is uniformly brownish-white; shield, legs and rostrum pale testaceous. The _larva_ varies from 0·88 mm. when fasting to 1·76 mm. when gorged. Its body is light, but gradually becomes darker, with similar intestinal marks to _ricinus_.

[This tick is very common, especially on ferrets, stoats and hedgehogs. It is also found on sheep, cattle, etc. The males do not generally occur in company with the females on the host. Pairing probably takes place on the ground.--F. V. T.]

Genus. *Amblyomma*, Koch.

*Amblyomma cayennense*, Koch, 1844.

Syn.: _Amblyomma mixtum_, Koch, 1844; _Ixodes herreræ_, Dugés, 1887;
_Amblyomma sculptum_, Berlese, 1888.

Characterized by the possession of eyes. The male measures 3·8 mm. in length by 3 mm. in breadth; the female 4 mm. in length by 3 mm. in breadth, but when full of blood may become 13 mm. in length and 11 mm. in breadth. They are common in the whole of Central America (Carrapatas), and attack mammals, amphibious animals and man.[340]

[340] Neumann, G. L., _loc. cit._, p. 205.

[This species was described by Fabricius. It occurs in Cayenne, Guiana, in Southern Texas, Florida, California, Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, Panama, Bermuda, Cuba, Jamaica, Trinidad, Colombia, Venezuela, French Guiana, Brazil, Paraguay and the Argentine. It is called the silver tick. It frequently attacks man. Schwarz and Bishopp (_Bull._ 105, U.S. Dept. Agric., p. 158) heard of one man whose legs were well covered with suppurating sores and who was ill from the attack of these ticks and the wounds produced by scratching, and records other cases of their swarming on man. Newstead (_Ann. Trop. Med. and Par._, 1909, iii, No. 4, p. 442) records it as the worst pest to man in Jamaica.--F. V. T.J

*Amblyomma americana*, Linnæus.

The so-called long star tick, from the silvery spot on the apex of the scutum of the female. It will attack any mammal and even birds and also man. It occurs in North America, and also in Brazil, Guiana and Guatemala. Its punctures frequently end in suppuration. In the Eastern and Southern States man is more frequently attacked by this species than any other. Moss-gatherers in Louisiana are badly attacked by it.[341] It also attacks the milkers in dairies. Attempts to transmit Texas fever failed with this species.

[341] Morgan, “Ticks and Texas Fever,” _Louisiana State Bull._ 55, pp. 134, 135, pl. 59.

*Amblyomma maculatum*, Koch.

The so-called Gulf Coast tick, of the Gulf Coast, occurs on birds, mammals and man, especially cattle, and attacks the ears.

Genus. *Hyalomma*, Koch.

*Hyalomma ægyptium*, L., 1758.

Syn.: _Acarus ægyptius_, L., 1758; _Ixodes camelinus_, Fischer, 1823.

A species frequently found in Africa, particularly in Egypt and Algeria, and which also occurs in France and Italy, as well as in Asia. Male 8 mm. in length, 4·5 mm. in breadth. Female up to 24 mm. in length and 15 mm. in breadth. It infests large and small animals as well as human beings.[342]

[342] Neumann, G. L., _loc. cit._, p. 285; Ronsisvalle, “Sui fenomeni morb. prodotti nel uomo da un Ixodide denominato _Hyal. æg._,” _Boll. Acc. Gioenia sci. nat._, 1891, xvii.

[This is one of the largest ticks, nearly reaching the size of the bont tick. It is known in Africa as the bont leg-tick; all farm stock is attacked, but sheep and goats suffer most. Only one generation appears to occur each year. The male is almost black with a pale marginal stripe; the replete female brown with irregular light blue stripes. It is abundant in parts of South Africa.]

Genus. *Hæmaphysalis*, Koch.

*Hæmaphysalis punctata*, Canestrini and Fanzago, 1877–1878.

Syn.: _Hæmaphysalis sulcata_, Canestrini and Fanzago, 1877–1878;
_Rhicocephalus expositicius_, Koch, 1877; _Hæmaphysalis peregrinus_,
Cambridge, 1889; _Herpetobia sulcata_, Canestrini, 1890.

[This species does not appear to be common. It occurs on sheep, goats, horses and cattle. I have seen a female taken from man in Britain. The female when fasting is 3·44 mm. long, when gorged 12 mm. long. Colour, reddish-brown, leaden-grey when gorged; dorsal shield deeply indented in front; rostrum, shield and legs brownish; body finely punctate, both above and below; sexual opening opposite the coxæ of the second pair of legs in both sexes. Palpi a little longer than the labium; first segment short and narrow, second and third widened on the dorsal face. Coxæ with a short, broad blunt spine; tarsi short, terminated with a spur on the first pair. The male is 3·10 mm. long. Body rather narrow, yellowish to reddish-brown; dorsal shield nearly covers the whole body; numerous punctures over the whole surface. Eleven indentations on the posterior margin of the body; peritremes lighter in colour, large and comma-shaped. The three anterior pairs of legs with a short spine on the haunches, the fourth with a very long one directed backwards. The nymph varies from 2·5 to 3·0 mm., is oval, and light yellow to dark red in colour. Dorsal shield rounded with few punctations. No spur on tarsi, and sexual orifice nearly obsolete. Larva short and oval. Length 1·20 mm.--F. V. T.]

Genus. *Dermacentor*, Koch.

*Dermacentor reticulatus*, Fabricius, 1794.

Syn.: _Acarus reticulatus_, Fabr., 1794; _Ixodes reticulatus_,
Latreille, 1806; _I. marmoratus_, Risso, 1826.

This tick is provided with eyes, but it is distinguished from Ixodes and analogous genera by the lack of the abdominal plastron in the male, which measures 5 to 6 mm. in length by 3·5 mm. in breadth. The female may attain 16 mm. in length and 10 mm. in breadth. It is found in the South of Europe, in Asia, and in America; it attacks chiefly oxen, sheep and goats, and occasionally man.[343]

[343] Neumann, G. L., “Rev. de la fam. des Ixodides,” _Mém. Soc. Zool. France_, 1897, x, p. 360.

[This tick sometimes causes much annoyance to human beings. It was once most troublesome at Revelstoke. Specimens have recently been found on fowls, turkeys and pheasants in Kent.

[Other synonyms are as follows: _Cynorhæstes pictus_, Hermann, 1804; _Crotonus variegatus_, Dumeril, 1829; _I. pictus_, Gervais, 1844; _Dermacentor albicollis_, Koch, 1844–1847; _D. pardalinus_, Koch, 1844–1847; _D. ferrugineus_, Koch, 1844–1847; _Ixodes holsatus_, Kolenati, 1857; _Pseudixodes-holsatus_, Haller, 1882; _Hæmaphysalis marmorata_, Berlese, 1887.

[The _female_ when fasting is 3·86 mm. long by 2 mm. wide. The body is depressed, larger behind and reddish-brown in colour. The shield is very large and extends to the level of the third pair of legs, with a few large and many small punctations, milky white, variegated with reddish-brown. Sexual orifice opposite the coxæ of the second pair of legs. Coxæ of the front legs are deeply bifid, the others with a moderate spine. When gorged light brown, and may reach 16 mm. When depositing eggs the female is mottled with dark brown above and below. The _male_ is like the female. The shield is reddish-brown, variegated with a milky white pattern. Coxæ of the fourth pair of legs three times the size of the third. There is a sharp backwardly pointing spine on the second palpal segment, also seen (but smaller) in the female. Length 4·20 mm.

[According to Mr. Wheler this is a very variable species both in size and colour. It occurs in England on sheep, but not commonly. It has probably been introduced into Britain. Besides the animals mentioned above it is also found on deer.--F. V. T.]

*Dermacentor venustus*, Banks.

[The Rocky Mountain tick fever tick. This species has been wrongly called _Dermatocentor reticulatus_ var. _occidentalis_. The correct name of the carrier of Rocky Mountain tick fever is _Dermacentor venustus_, Banks (Hooker, Bishopp and Wood, _Bull._ 106, U.S. Dept. Agric., Div. Ent., p. 165).

[The female is from 13·8 by 10 by 6·4 mm. to 16·5 by 11·4 by 6·9 mm. when gorged; the male from 2·1 by 1·5 mm. to 6 by 3·7 by 1·4 mm. The male reddish-brown; scutum with an extensive pattern of white lines, usually but little white on the mid-posterior region, legs slightly lighter than scutum, joints tipped with white. Female with scutum mostly covered with white, abdomen reddish-brown, legs as in male. The nymph when unengorged reddish-brown, when gorged dark bluish-grey; the larva is yellowish-brown when unengorged, slate blue when engorged. The ova light brown, shiny and smooth.

[The chief wild hosts are the brown bear, coyote, woodchuck, rabbit, wild cat, badger and mountain goat for the larvæ; practically all small mammals act as hosts for larvæ and nymphæ, whilst the adults are seldom found on other than large domestic animals; horses and cattle are preferred. It occurs in British Columbia, southward to Northern New Mexico, and from the foothills of the Rocky Mountains in Colorado to the base of the Cascade Range in Oregon and California; abundant in Western Montana, Idaho, Eastern Washington, Oregon, North Utah, West Wyoming and North-west Colorado.

[Of great importance in the Bitter Root Valley of Montana, where a number of cases of fever occur each year, with a mortality of about 70 per cent. In British Columbia this tick causes tick paralysis in man and sheep. Only the adults seem to attack man and animals there (Hadwen and Nuttall, _Parasitology_, 1913, vi, No. 3, pp. 288–297 and 298–301) according to the _Canadian Medical Association Journal_, December, 1912. The symptoms are unlike spotted fever. For full details of this tick _vide Bulls._ 105 and 106, U.S. Dept. Agric.]

*Dermacentor occidentalis*, Neumann.

This tick only occurs in the Pacific Coast region of the United States. Owing to the fact that it frequently attacks man as well as occurring in great abundance in Oregon and California, it is of considerable economic importance. It is spoken of as the wood tick, and in the regions where found is the most common tick to attack man. Hooker, Bishopp and Wood (_Bull._ 106, U.S. Dept. Agric., Div. Ent., 1912, p. 189) state that a number of cases have been brought to their notice where the bite of this tick has caused considerable local inflammation, which in some cases required physicians’ attention. It has been supposed to be connected with Rocky Mountain spotted fever, but it is doubtful if it is concerned in its transmission. The engorged female is steel grey, the dorsum with an olive-green surface colour, which covers the grey except in small spots, giving a mottled appearance. The unengorged males and females are reddish-brown, scutum covered with a whitish bloom, interrupted by many red punctures. The female is 9 by 6·1 by 3·3 mm. to 11·8 by 7·6 by 5·6 mm.; the male 2·8 by 1·6 mm. to 4·2 by 2·3 mm. The larvæ are bluish-grey when engorged, reddish-brown when unengorged. The nymph is light brown, sides of scutum darker, and the intestines dark brown. It is confined to the Coast Range and Sierra Nevada Mountains in California and Oregon and the small mountain range to the south-west.

*Dermacentor variabilis*, Say.

The American dog tick has also been found on man, but it is of little economic importance as it is easily removed from its host.

Genus. *Margaropus*, Karsch.

*Margaropus annulatus australis*, Fuller.

The so-called Australian cattle tick. Newstead[344] reports this as a great pest to man in Jamaica in its larval stage. Its chief hosts are cattle, horses, goats, sheep, dogs and rabbits.

[344] _Ann. Trop. Med. and Par._, 1909, iii, No. 4.

*Margaropus microplus*, Canestrini.

Recorded by Aragão (_Mem. Inst. Oswaldo Cruz_, 1911, iii, fasc. 2, p. 163) as occurring in larval stage on man in Brazil.

Genus. *Rhipicephalus*, Koch.

*Rhipicephalus sanguineus*, Latreille, 1804.

Syn.: _Ixodes sanguineus_, Latr., 1804; _I. rufus_, Koch, 1844;
_Rhipicephalus limbatus_, Koch, 1844; _Rh. siculus_, Koch, 1844; _Rh.
stigmaticus_, Gerstäcker, 1873.

Spread over almost the entire tropical and sub-tropical regions, occurring in Europe in the South of France and in Italy; it infests dogs and more rarely sheep; oxen, cats, foxes and human beings are also attacked.[345]

[345] Neumann, G. L., _loc. cit._, 1897, p. 385.

NEUMANN’S TABLE OF SPECIES OF ARGAS.

1 {Body elliptical (sides curved) 2.
{Body oblong (sides straight), ending anteriorly
{ in a point 7.
2 {Body transversely oval _vespertilionis_.
{Body elongate oval 3.
3 {Margin of body striated 4.
{Margin of body formed by quadrangular areolæ PERSICUS.
4 {Body flat, integument plainly wrinkled 5.
{Body tumid, elongate; integument finely
{ wrinkled; coxæ of fourth pair of legs near
{ anterior third of body _hermanii_.
5 {Body oval, narrowed anteriorly REFLEXUS.
{Body elliptical, blunt, hardly narrowed
{ anteriorly 6.
6 {Body twice as long as broad _cucumerinus_.
{Body hardly longer than broad _transgariepinus_.
7 {Dorsal integument with large polygonal
{ depressions; tarsi appearing bifid BRUMPTII.
{Dorsal integument almost smooth; tarsi not
{ appearing bifid _æqualis_.

The _Argantinæ_ are distinguished from the _Ixodinæ_ by the head,
which in the former is situated on the inferior aspect of the
cephalothorax, while in the _Ixodinæ_ it projects freely; also by
the very short proboscis, the small club-like palpi, the lack of
suckers on the legs, as well as by the scutellum, which covers
the entire back and is bent up round the borders. Two genera are
distinguished: Argas, Latreille, 1796 (Rhynchoprion, Hermann, 1804),
and Ornithodorus, Koch, 1844. The species live on mammals, but more
especially on birds.

Genus. *Argas*, Latreille.

*Argas reflexus*, Fabricius, 1794.

Syn.: _Acarus reflexus_, Fabricius, 1794; _A. marginatus_, Fabricius,
1794; _Rhynchoprion columbæ_, Hermann, 1804.

The European marginated tick, _Argas reflexus_ (length of male 4 mm., breadth 3 mm., length of female 6 to 8 mm., breadth 4 mm.), is of a yellowish colour and has yellowish-white legs. The ingested blood shows red or brown through the intestine, which is provided with blind sacs. It lives in dovecots. It remains hidden during the day and at night crawls on to the sleeping pigeons to suck their blood. It has been observed in France, England, Italy, Germany, and Russia. Persons sleeping near infected dovecots, or in apartments formed from pigeon-lofts, are also attacked, even when the room in question has not been used for sheltering pigeons for years, as “marginated ticks” can live in a fasting condition for a very long time. The bite sometimes gives rise to serious symptoms, such as general erythema and sudden œdema.

[This pest more often feeds on the blood of man than is imagined. Blanchard states that he has received them from men’s clothes in Strasburg. Boschulte, of Westphalia, records these parasites in a bedroom inhabited by children and connected with a pigeon-house. The children were bitten during sleep on the hands and feet. The result of the bite was intense itching along the nerves, the bite only being marked by a red spot. In a girl of 14 or 15, vesicles were formed similar to those produced by burns, and in an old man an ulcer formed. Others record painful punctures and persistent œdema produced by this pigeon pest. It was once abundant in Canterbury Cathedral, and often caused much annoyance, I am told, to the worshippers; the ticks falling down from the roof, where they were living, derived from the numerous pigeons that breed in the towers. This Acarus has enormous powers of vitality, living without food for months at a time.--F. V. T.]

*Argas persicus*, Fischer de Waldheim, 1824.

Of oval form and brownish-red colour. The male measures 4 to 5 mm. in length by 3 mm. in breadth; the female 7 to 10 mm. in length by 5 to 6 mm. in breadth. It frequents the entire north-west and north-east of Persia (the gerib-gez or malleh of the Persians, the miana bug of travellers). It lives concealed in houses and attacks man at night to suck his blood. Its bite is much dreaded, but the serious results may probably be attributed to unsuitable treatment of the wound or its invasion by bacteria.

[This tick, sometimes called the tampan and wandlius in South Africa, is mainly a fowl parasite. Fowls and ducks frequently die under its attack, particularly young ones, death being due to loss of blood. This tick remains attached to its host during its larval stage for about five days; it then leaves and moults in concealment. In its subsequent stages it visits its host by night and remains for about an hour only, during which time it distends itself fully with blood. As a nymph it moults twice, not once as do the cattle ticks. This tick and other Argas become larger with each moult, but retain their same general appearance. The female visits the host every now and then, and, between, deposits eggs in sheltered crevices. About fifty to 120 are deposited at once. Four weeks seems a necessary period to intervene between visits to the host, and the interval may be extended to upwards of a year according to Lounsbury.[346]

[346] “Report of Government Entomologist, Cape of Good Hope, for 1899,” 1900, p. 33.

[It is found in the Sudan, where Balfour has found granules derived from the segmentation of spirilla in their digestive tract. Fantham and Hindl have confirmed this. It has been assumed that these granules carry infection.

[This so-called Persian tick, the miana, which is such a scourge to travellers in Persia, appears to infest the huts of natives in that country. It has been sent me from Quetta, where it has invaded houses to such an extent the natives cannot live in them. The virulence of its bite is probably due to the tick transmitting fever germs from natives, probably inured, to strangers, who would be susceptible.--F. V. T.]

*Argas brumpti*, Neumann.

[Found in Somaliland, by Brumpt, and in the Sudan. This tick attacks man as well as wild animals and produces a painful swelling according to King,[347] but as pointed out by that naturalist it probably relies on other than human food.--F. V. T.]

[347] “Fourth Report Wellcome Res. Labs.,” 1911, p. 128.

*Argas chinche*, Gervais, 1844.

This Acarus, a native of the temperate parts of Colombia, is very troublesome to man. It is probably identical with _A. americanus_, Packard, which infests domestic fowls and turkeys, and occasionally also cattle, and is differentiated from _A. reflexus_ by the sculpturing of the cuticle.

Genus. *Ornithodorus*, Koch.

Neumann’s SYNOPSIS OF THE GENUS ORNITHODORUS is as follows:--

{ Hypostome unarmed; integument in nymph stage and
1 { partly in adult spinulose MÉGNINI.
{ Hypostome armed with recurved teeth; integument
{ not spinulose 2.
2 { Camerostome with movable lateral flaps TALAJE.
{ Camerostome without movable lateral flaps 3.
{ Anterior border of distal segments of legs with
3 { tubercles or festoons 4.
{ Anterior border of segments of legs without
{ tubercles or festoons 8.
4 { Body not much contracted anteriorly 5.
{ Body pointed anteriorly 7.
{ Tubercles of distal segments of legs higher than
{ broad, distant 6.
5 { Festoons of distal segments of legs as broad as
{ high, contiguous _pavimentosus_.
6 { Eyes present SAVIGNYI.
{ No eyes MOUBATA.
7 { Eyes present _coriaceus_.
{ No eyes TURICATA.
8 { Integument with fine radiating wrinkles _lahorensis_.
{ Integument granular 9.
9 { Tarsi appearing bifid at apex _furcosus_.
{ Tarsi not appearing bifid at apex 10.
{ Tarsi of first pair of legs with three dorsal
10 { tubercles, of other legs with one _canestrinii_.
{ Tarsi without dorsal tubercles or with only one 11.
{ Tarsi of last three pairs of legs with pronounced
11 { dorsal protuberance _tholozanii_.
{ Tarsi of legs with indistinct dorsal protuberance _erraticus_.

*Ornithodorus moubata*, Murray, 1877.

An abundant African tick which is one of the carriers of the spirillum of African relapsing fever and can also carry _Filaria perstans_ (Christy). Its body is oval, yellowish-brown when young, greenish-brown when mature. The integument is covered with mamillose tubercles. No eyes and the stout legs granular above, the tibiæ and tarsi fringed with tubercles on the upper side. Pocock[348] records it from Uganda and German East Africa, Congo and Angola, to Namaqualand and the Transvaal in the south. It is called _bibo_ in Uganda, _moubata_ in Angola, and _tampan_ on the Lower Zambesi. It feeds on animals and birds as well as man. Its bite is very painful. This tick is found in native huts, living in cracks and crevices and in the thatch roofs.

[348] “A System of Medicine,” Allbutt and Rolleston, i, pt. 2, p. 195.

The female tick infected with the spirillum transmits the infection to the eggs and the next generation. They appear to be able to live without food a long time, and probably live for years. They lay their eggs in masses on the ground or in crevices, and when they hatch they are in the nymph stage with four pairs of legs. _O. moubata_ also occurs in Madagascar with recurrent fever (Lamoureux, _Bull. Soc. Path, exot._, 1913, vi, No. 3, pp. 146–149).

*Ornithodorus savignyi*, Audouin, 1827.

At one time considered the same as the preceding species, but can be easily separated by the presence of two pairs of eyes. It is widely spread over Africa and has been found in South India and at Aden. In the Sudan it occurs in large numbers. King[349] records that a few miles N.N.E. of Khartoum 370 specimens were collected in two hours under a single tree by a well. It is found in Somaliland, where relapsing fever occurs and no _O. moubata_, which it probably replaces as a transmitter (Drake-Brockman, “Rep. Col. Office,” April 6 and April 16, 1913). It also occurs in Tunis, where the natives call it “tobbiah” (Weiss, _Arch. de l’Inst. Pasteur de Tunis_, 1912, pt. 4, p. 226).

[349] “Fourth Report Wellcome Res. Labs.,” 1911, B, p. 129.

*Ornithodorus coriaceus*, Koch.

Found in Mexico, Paraguay and California. Attacks man.

*Ornithodorus talaje*, Guerin, 1849.

An eyeless species with somewhat elongate pentagonal body found in Mexico and South America, called the “chinche.” A variety of it (_coniceps_) is found at Venice, etc., and another variety on various islands in the Indian Ocean and South Atlantic. Its bite is very painful to man.

*Ornithodorus turicata*, Dugès, 1876.

Without eyes. Indigenous in Central America; attacks human beings and pigs. The bite is painful and is often followed by serious consequences.

[So virulent is this species that pigs put in an infested sty often die in a night. This “turicatas” of Mexico often reaches 6 mm. in length.--F. V. T.]

*Ornithodorus tholozani*, Laboulbène and Mégnin, 1882.

Syn.: _Argas tholozani_, Lab. and Még., 1882.

Without eyes. Males 4 to 6 mm. in length and 2 to 4 mm. in breadth; females 8 to 10 mm. in length and 4 to 5 mm. in breadth. It especially attacks sheep. Native of Persia and Asia Minor.

[This species is reputed as being very dangerous to man. It is locally know as the kéné, or sheep-bug. In its fully gorged state it is deep violet.--F. V. T.]

*Ornithodorus mégnini*, Dugès, 1883.

Syn.: _Argas mégnini_, Dugès, 1883.

Length 8·5 mm., breadth 5·5 mm. Native of Mexico.

[Another synonym for this species is _Rhynchoprion spinosum_, Marx. The adult males and females are grey to dark brown, the male somewhat the smaller; female 5 by 3·5 by 2·5 mm. to 10 by 6 by 3·5 mm. The larvæ at the seed tick stage are dark grey, turning to pink, then to a whitish grey when engorged. The nymph when young is blood-red in front, rest pearly white; later they turn reddish-brown.

[Intense pain may be caused by its presence in and around the ears.

[Two specimens in the nymphal state were taken from the ears of a visitor to Cambridge by Dr. J. Christian Simpson. They were supposed to have entered the ears when the gentleman was camping out in Arizona (_Lancet_, 1901, i, No. 4,052, p. 1198, fig. 3).

[This species attacks the horse, ass, dog, cats and oxen, generally around the ears, and also attacks man. It is well known in the United States as infesting the ears of children (_New York Ent. Soc. Journ._, 1893, pp. 49–52).

[It occurs in Texas, Arizona, New Mexico and California as well as Mexico, Brazil, and possibly many parts of South America; and recently Bedford (“Sec. Report Div. Vet. Res., S. African Union,” 1912, pp. 343, 344) has shown it to occur at Vryburg and Fauresmith, in the Transvaal, on stock. It also occurs in the Sudan.--F. V. T.]

OTHER LITERATURE ON _Ixodidæ_.

(1) “Pénétration de l’_Ixodes ricinus_ sous la peau de l’homme,”
_Compt. rend. Soc. de Biol._, 1891, xliii, ser. 9, iii, pp. 689–691,
R. Blanchard.

(2) “Notas sobre Ixodidas brazileiros,” _Mem. Inst. Oswaldo
Cruz_, 1911, iii, fasc. 2, pp. 145–195, pls. 11 and 12, Dr. H. de
Beaurepaire Aragão. Table of Brazilian Species.

(3) “Contribuicão para a sistematica e biolojia dos Ixodidas,” _Mem.
Inst. Oswaldo Cruz_, 1912, iv, fasc. 1, pp. 96–120, pls. 2 and 3, Dr.
H. de Beaurepaire Aragão.

Family. *Tyroglyphidæ.*

Very small mites without eyes and without tracheæ, with smooth skin.

The males usually have a suctorial pore on either side of the anus,
which is used during copulation, or suckers may be found in both
sexes near the sexual orifice. The mouth parts form a cone with
chelate cheliceræ, and three-jointed pedipalpi; the legs are usually
short, have five segments with a terminal claw and suckers, or either
one or other of these organs. The numerous species and genera live
free and from choice in slowly decomposing vegetable and animal
matter (cheese, cereals, flour, sugar, preserves, dried anatomical
preparations, bacon, dried fruits and fungi), also in the corners
of dwellings, etc.; they incidentally get into or on to man, or are
found in chamber utensils and in spittoons; actual parasites are
rarely found amongst them.

[The chief genera are Tyroglyphus, Rhizoglyphus, Glyciphagus,
Aleurobius and Histiogaster. The first three have typical characters
referred to, but are distinguished from each other by the two
former having the hairs on the dorsum smooth, whilst in Glyciphagus
they are hairy, plumose, or feathered. Rhizoglyphus can be told
from Tyroglyphus by having claws on the tarsi without any suckers;
Tyroglyphus has both claws and suckers. The larvæ are hexapod and
may become adult in the usual way by repeated moults, or they enter
the so-called hypopial stage. In this the eight-legged nymph becomes
quiescent, and during this stage it fixes itself to some insect or
other animal by a patch of suckers on the lower surface of the hind
end of the body, and is so carried from place to place. The hypopus
does not feed and has a hard shell and short legs. When it has
reached a new home it moults and development proceeds in the normal
way. Canestrini and Kramer treat the _Tyroglyphidæ_ as a sub-family
of the _Sarcoptidæ_, calling them sub-family _Tyroglyphinæ_,
the other sub-families being _Sarcoptinæ_, _Canestriniinæ_ and
_Analsinæ_.--F. V. T.]

Sub-family. *Tyroglyphinæ.*

Genus. *Aleurobius*, Canestrini.

*Aleurobius* (*Tyroglyphus*) *farinæ*, de Geer (part), Koch.

The male measures 0·33 mm. in length by 0·16 mm. in breadth; the female 0·6 mm. in length by 0·3 mm. in breadth. These mites possess five pairs of suctorial organs of a light colour; the legs are reddish. Moniez observed them in Lille on the skin of labourers who had been unloading Russian corn. A few of the species generally mentioned under the designation of _Tyroglyphus siro_ are probably the common flour-mite, which also occurs on dry cheese.

[The _farinæ_ of de Geer is an Aleurobius described by him in 1778 (“Mém. Hist. Ins.,” vii, t. 5, f. 15, p. 97) as _Acarus farinæ_.--F. V. T.]

Genus. *Tyroglyphus*, Latreille.

*Tyroglyphus siro*, L., 1756.

(Defined by Gervais, 1844.)