316 CLASS VIII. 



hairy, yellow, thorax in the middle black, wings with a brown-grey, trans- 

 verse stripe in the middle and two similar spots at the point ; the female 

 has a long black ovipositor at the end of the abdomen. This fly lays her 

 yellow eggs in various situations on the hair of the horse, to which they 

 remain firmly attached by a glutinous fluid. The young larvae come from 

 the eggs, which spring open by a lid, as very long and active little worms, 

 and are conveyed by the lick of the horse's tongue into his mouth and 

 gullet (with respect to those eggs which lie beyond the reach of the tongue, 

 we may suppose, with NUMAN, that the larvae themselves creep to other 

 situations nearer the head). Subsequently the larvae live in the stomach of 

 the horse, to which they have become attached in very great numbers 

 (several hundreds at once). Here they remain several months, from spring 

 till the beginning or middle of summer, then are detached, being expelled with 

 the excrement, and change into pupae, from which, after about five weeks, 

 the perfect insect comes to view. This species is found in the horse and 

 ass ; besides these, and sometimes simultaneously with them, larvae also of 

 other species (Gaslrus hcemorrhoidalis for instance) live in the same resort ; 

 the larvae of this last species are smaller and deep red ; see NUMAN, PL n. 

 fig. i. 



(Eslrus JowsFABR., MEIG., GUERIN, Iconogr., Ins. PL ioi,fig. 3, CLARK, 

 1. 1. PI. n. figs. 8, 9, Cuv. R. An., ed. ill., Ins. PL 176, fig. 2. The larva 

 of this species lives under the skin of the bullock ; that of (Estrus (Cephale- 

 myia) ovis L., GUERIN, Icon. Ins. PL 101, fig. 4, MEIGEN, Syst. Beschr. iv. 

 PL 38, fig, 1 6, lives in the frontal sinuses of the sheep 1 . 



Phalanx II. Proboscis distinct. Two setae of haustellum. 



A. Muscarice (species from genus Musca L.) Proboscis distinct, 

 membranous, retractile, bilabiate at the point. 



Though the Fly genus (Musca), thus defined, be much smaller 

 than that of LINNAEUS, it is still a very extensive group, in which 

 the moderns distinguish many genera. Here may be compared 

 ROBINEAU DESVOIDY, Essai sur les Myodaires, Mem. presentes a 

 FAcad. des Sc. de Ulnstitut de France, Tom. n. 1830, 4 to. 



1 A species is spoken of in man: (Estrus hominis (GMEL., Syst. nat. Ed. 13, I. 

 p. 2811) ; comp. KIRBY and SPENCE, Introduc. to Entomol. I. pp, 136, 137. Of later 

 observations ISID. GEOFFROY SAINT-HILAIRE has given an account in the Ann. de 

 la Soc. Entom. n. p. 518. That larvae of (Estrus bovis and of other Diptera may 

 sometimes live under the skin of man is probable from some observations ; a few years 

 ago an insect was shewn me that had come out of a boil under the skin in a girl, 

 it was the pupa of a dipterum, and agreed very well with that of (Estrus. A 

 larva which in many respects resembled that of a Tachina, but yet differed from all 

 the species of larvae of Diptera yet known, was observed by Dr SMITT ; this larva 

 was pressed from a boil on the head of a girl 63 years old ; see J. J. SMITT and 

 C. J. SONDEVALL, Veterslc. Alcad, Handlingar, Stockholm, 1840, pp. 63 68. 



