DIPTERA. 631 



scaly i^Me at the posterior extremity of the I)ody, -u'hieh is thickest. It appears that their number 

 and arrangement are difterent in tlie gastric larvpe : it also appears that the mouth of the cutaneous 

 larvai is only composed of fleshy lobes, whilst that of the internal larvae is armed with two strong, 

 bent hooks. 



When the larvae have obtained their full size, they quit their former abode, fall to the earth, and 

 there hiile themselves, in order to undergo those transformations to pupa; beneath their own skin, like 

 the other Diptera of this division. 'Die gastric larvae pass through the intestines and escape by the 

 anus, probably with the excrement. It is generally in June and July that these changes take place. 



M. Humboldt has observed, in South America, Indians with the abdomen covered with small 

 tumours, produced, as he believed, by the larvae of (Estri ; and later observations appear to confirm 

 this opinion. These larvjc probably belonged to the genus Cuterebra of Clark, the larvse of which 

 reside beneath tiie skin of several raammiferous animals. It also appears, from various testimony, 

 that larvse analogous to those (Estri have been extracted from the maxillary or frontal sinuses of 

 Man ; but these observations have not been pursued. 



Some have a small and retractile proboscis. 



Cuterebra, Clark, has the seta of the antenna? plumose, and the palpi not visible. Oestrus huccatus, Fab. ; 

 Ciaricull, Clark ; and Ephipp'n/rn, Latr. ; all from America. 



Cephencmyia, Latr., has the seta sinjple, antl the patpi evident. (Estrus Trompe, Fab., the larva of which infests 

 the frontal sinus of the Uein-fleer. 



The others have no proboscis, and the seta of the antennas is always simple. 



(Edemagena, Latr., has two palpi. (Efitms Taraiidi, the Bot of the Rein-deer. 



The following; have no palpi. 



Jli/poderma, Latr., with a small oral aperture like a Y. CEitrus Boris, the lai'va of which resides in tumours on 

 the back of Oxen. 



Cephalcmyia, Latr., has two small tubercles like points, which are the vesti;2;es of palpi ; the alulets cover the 

 balancers. CEsfrus Ovls, the Sheep Bot-fly, the larva of which lives in the frontal sinuses of the Sheep. 



CE.strus proper (Gasfnis, Me\g., Ganterojyhilns, Leach), has two similar tubercles, 

 but the wings cross each other, and the alulets only partially cover the halteres. 



CEstrus Equi, the Great Horse Bot, h^emorrhoidalis, vei(n-imis, &c. This differs 

 in the cells, extending to the hind edge of the wings, whereas in all the rest (which 

 Leach and Meigen retain under the name of (Estrua) the cells are closed before reach- 

 ing tlie hind margin. 



The third tribe of the Athericera, that of the Conopsari^, is the only 



one in which the proboscis is always exserted and siphon-shaped, either cylin- 



^^^^,^^=3™^^g=,^ dric, conical, or setaceous. The reticulation of the wings is tlic same as in 



-)|j ll^-- -'^■^f^ our first division of Mascides. The majority of these insects are found on 



<ii,.tfj. ■ ""=^" plants. They compose the genus 



Fiy. 13fi.— Gasteropliilus equi CONOPS, LiuuiCUS. 



Some have the body long and narrow ; the abdomen long, clavate, and bent under at the tip, with 

 the male organs exposed. 



One portion of these has the proboscis only elbowed at the base. 



Si/sfropns, Wied. (Cephenen, Latr.), has the antennae much longer than the head, the last joint alone forming 

 the club, without a style, and the abdomen long and slender. South American insects, like small species 

 oi' Sph ex. 



Coiiops proper, has the antenna much longer than the head, and the last two joints form together a mass, with 

 a terminal style. 



Coriops rujipcs. Fab., which undergoes its transformations in the interior of the body of living Bombi. escaping 

 between the segments. An apod larva, found in Bomhus lapidarius, being probably that of this species, has fur- 

 nished Messrs. Audouin and Lachat materials for some tine anatomical observations. 



Zodion, Latr., has the antennae shorter than the head, terminating in an ovoid mass. 



Mi/opa, Fab., has the proboscis elbowed at the base, and again near the middle, the apex being bent under, and 

 the antenn.T shorter than the head. [Several British species.] 



The others (Stomoxi/da, Meig.), resemble domestic FUes in their general form, the arrangement of 

 their wings, the antennae terminated by a palette shorter than the head, and furnished with a seta, 

 and the abdomen short and conical, without external appendages. 



lS(u)uox'/s proper, has the proboscis only elbowed at the base. T^-pe, Conops calcitrans, Linn, [a very common 

 insect, often observed on windows, and which is the specie.s] which pricks our legs so sharply, especially 

 before ram. 



