382 INSECTA. 



The body is short, tolerably broad, flattened and defended by a 

 solid skin almost of the consistence of leather. The head is more in- 

 timately united to the thorax than in the preceding families. The 

 antennae, always situated at the lateral and anterior extremities of the 

 head, sometimes form a tubercle bearing three setse, and sometimes 

 little hairy laminee. The eyes vary as to size ; in some species they 

 are very small. 



M. Leon Dufour, in his description of the Ornithomyie bilobee, 

 has observed, that although this genus has had ocelli attributed to it, 

 he has not been able to discover them. A fresh examination of such 

 species as I could procure has in fact convinced me that we were 

 mistaken*, and it may be considered as a general rule that the Pupi- 

 para are destitute of those organs. The thorax presents four stig- 

 mata, two anterior and two posterior. The learned entomologist 

 just referred to, in the Hippobosca equina of which he has described 

 the Anatomy — Ann. des Sc. Nat., VI, 299, et seq. — could only find 

 the two first, those which are situated on the lateral and anterior ex- 

 tromities of the mesothorax ; but I have discovered the two others in 

 the same Insect. They are situated, as in other Diptera, near the 

 origin of the halteres. The abdomen of the Hippobosca ovina — see 

 Melophagus — presents ten, in the form of little round, corneous, um- 

 bilicated tubercles, the four last being approximated to the anus. 

 Those of the thorax, always four, are very apparent. According to 

 the same observer, the interior of this part of the body in the H. 

 equina presents both utricular and tubular trachae ; but those of the 

 abdomen are all of the latter description and very numerous. 



The wings are always distant and accompanied by halteres. Their 

 edge is more or less fringed with cilia. The superior nervures which 

 are in its vicinity are strong and very distinct ; but those which then 

 extend to the posterior margin are but slightly marked and are not 

 united transversely. In the last Diptera of this family, these organs 

 are wanting or are merely rudimental. The halteres also disappear. 

 The legs are very distant and terminated by two robust nails with 

 one or two teeth beneath, which makes them appear double or triple. 

 The skin of the abdomen is formed of a continuous membrane, so 

 that this part of the body is susceptible of being distended and of ac- 

 quiring a considerable volume, as necessarily happens in those female 

 Hippoboscte, where the larvae are hatched and continue to reside until 

 the period of their transformation into pupae. At this epoch the larvae 

 issue from the venter of the mother in the form of a soft, white egg, 

 almost as bulky as the maternal abdomen ; the skin hardens and be- 

 * Dr. Leach, however, admits that they exist in certain species. 



