DJPTERA. C37 



general the pnpipara; are destitute of ocelli ; the thorax is furnished with four spiracles, two anterior 

 and two poslerior; the latter pair, overlooked hy Dnfour, are situated, as in other Diptera, near the 

 hasi^ of the balanciTs. The a1)dnineu of //. ovina is furnished witli ten spiracles, in the shape of 

 snifill, round, corneous tubercles, the four posterior beine; close to the anus. Tiie wings are always 

 apart, and accompanied by balancers ; their [fore-edge] is more or less margined with seta; ; the supe- 

 rior nerves, which are nearest it, are strong and well defined; but those which extend to the hinder 

 edge are weak, and not transversely united. In the terminal Diptera of this family these organs 

 are wanting, or simply rudimental; the balancers are also obsolete. The legs are terminated by two 

 robust claws, which have one or two teeth on the under side, which makes their appearance double 

 or triple. The covering of the abdomen is continuons, so that this part of the body can be distended, 

 and acquire a considerable volume, as becomes necessary in the body of the female Hippohoscoi, for 

 their larvae are hatched and are nourished therein until the period of their transformation into pup^. 

 They are then discliarged under the form of a soft, white t^^, nearly as large as the abdomen of the 

 female ; the skin hardens, and becomes a solid cocoon, brown at first, but suhserpiently black ; round, 

 and nff.L'u notched at one end, exhibiting a shiny plate or operculum, which becomes detached like a 

 cap at the period of the tinal transformation. This eocoon has neither rings nor transverse incisions 

 by which it is distinguished from those of other Diptera, especially the Athericera, which it most 

 resembles. It is in the fine w^orks of Reaumur, De Geer, Leon Dufour [and Lyonnet], illustrated as 

 they are by figures in detail, that we must look for a complete account of these transformations, and 

 of the changes which take place in the female at the period of her delivery. According to L. Dufour, 

 the ovaries in their configuration and position singularly resemble those of the human female. The 

 matrix, at first small, becomes enormously dilated, until it occupies the whole of the abdominal cavity. 



These Diptera are known under the name of Spider-flies, and live almost exclusively upon some 

 quadrupeds and birds. They run very quickly, and fly sideways. 



Some, or the Coriacea, Latr., have the head distinct, and articulated with tlie anterior extremity of 



the thorax. Tlic\' form the genus 



HippOBOSCA, Linnfeus. 



Uippobosca proper, has wini^e. distinct eyes, and antennfe in the shape of tubercles, ^^'ith three set;r on their 

 upper side. H. equina, Linn., tlie I-Jorse- or Forest-fly, a species common in some places on Horses, \ihich it 

 infests, especially tixinp; itself in great numbers beneath the tail. 



OniUhomiiia, Latr., has the antenuie in the shape of viUose plates, and the nerves of the wings extending to 

 the hind edii^e. 



These insects form, in the monocTaph of Leach, four genera. 



Feronia {Nirmomijla, Nitzscli.), di^itinct by the antennae-like tnbercles, and the claws of the tarsi double, and 

 not treble. 



Oniffhomi/ia, with ocelli and tridentate claws, plate-like antenns, and wings of large size, and rounded. 



Stenepteryx, simihir to Feronia, but with very long acute win^^s. 



Oxjipterum, with acute wings, but with the antenna; in the furni of teeth, eyes small, ocelli wanting. They live 

 on various species of Birds. Uippobosca avicularia, Linn. 



StrcOia, Wied., lias the wings incumbent on the body, with lon^ritudinat nervures united by some transverse 

 nervures. The eyes are very small, and situated at the posterior angles of the head. Found on a South American 

 species of Bat. 



Melophagiis, Latr. (Melophila, Nitzsch.), destitute of wings, and with the eyes scarcely distinct. Uippobosca 

 ovina, [the common Sheep-tick]. 



A species of Melophagus, which lives on the Stag, exhibiting rudiments of \Tine;s, and with the thorax a little 

 lar<^er than the head, forms the subgenus Lipopfena, Nitzsch. Near Jlelophagus ought also to come the genus 

 Braiila, Nitzsch., of whicli the only known species lives on the Honey-bee, and is absolutely blind. Its thorax 

 is divided into two transverse parts, and the last joint of the tarsi is furnished with a row of small bristles. 

 Reaumur had lonp; ago tigured this, or a closely-allied animal. 



The other Pupijiarx, Vldliiromy'KE, Latr., have the head very small, or almost obsolete, forming near 

 the anterior and dorsal extremity of the thorax a small body, which is elevated vertically. They 



compose the genus 



Nycteribia, Latr. (Pltthiridium, Hermann), — 

 And have neither wings nor balancers, and more nearly resemble Spiders than Hippoboscss. They live on Bats. 

 LinutTus places the only species with which he was acquainted with the PedicuU. See the article Nt/cicribia^ in 

 the Enci/clopedie Mef/wdique, and in the Nouv. Dicl/onn. d'H/if. Naiurel/e, [and also my memoir in the Transac- 

 iions of the Zoological >Sociehj of London, in which I have described numerous species]. 



