Carpenter & Hewitt — Genitalia and Larva of the Warhle-JI//. 273 



represents tlie tergum of tlie ninth neyntent; from comparison with the tip 

 of the abdomen in the male, we have little doubt that the terminal 

 part (T. 10) in the female belongs to the tenth segment. At its extremity 

 this sclerite is bent ventralwards, and ends in a fine point (figs. 11, 18, 

 T. 10). Articulating with the front part of this dorsal plate are a pair 

 of latero-sternal sclerites (figs. 8, 10, 11, 16, 17, 18, St. 9), rounded and 

 somewhat spinose, which doubtless belong to the ninth segment. These 

 are prolonged backwards into a pair of blunt, curved, hook-like processes 

 (P. 9), the " anal scales " of Lowne ('95), or " superior forceps " of 

 Wesch^ {'06), which must i^robably also be regarded as outgrowths of 

 the ninth segment ; they are beset with hairs and somewhat strong spines, 

 and in H. bovis each bears a sharp, inwardly directed prominence (fig. 9). 

 Being present in both sexes, they might be thought to correspond to what 

 have been regarded as eerci by some students of the anatomy of the Diptera. 

 In such primitive insects as the Mycetophilidse, however, the cerci are 

 jointed in the female and clearly belong to the tenth segment. Together 

 with the tip of the dorsal plate (T. 10) and the two ventral processes (P. 8), 

 these hook-like structures (P. 9} surround the vulva opening beneath the 

 eighth segment, and all five sclerites are joined by membranous cuticle 

 which is stretched when an egg is being laid. Then (fig. 7) the tergal 

 plate and the hook-processes are diverted dorsalwards, the ventral processes 

 remaining almost vertical. We can find no trace of a median ventral sclerite, 

 such as is described by Lowne in Musea. The hindmost dorsal tergum is 

 immediately over the anus. We are interested to find that, although the 

 jaws in Hypoderma are much reduced and feeding appears to be impossible, 

 the food-canal extends through the body ; the terminal part of the intestine 

 (fig. 1, in.) leads into a wide rectum (r.), in whose wall characteristic rectal 

 glands (r. g.) like those of Musca and Calliphora can be plainly seen. 



The hinder edge of each segment of the ovipositor is fringed with a few 

 hairs. We have been struck with the beautiful reticulate appearance of the 

 segmental cuticle between the hinder sclerites, showing a remarkable 

 pattern in black and white (see figs. 8, 11, 16, 18). The intersegmental 

 cuticle is closely beset with curious spines which have flattened bases 

 and one, two, or three points each ; these exquisitely formed structures are 

 stronger in H. bovis (fig. 12) than in II. lineatum (fig. 19). Their points are 

 directed forwards when the ovipositor is protruded ; but when the organ is 

 withdrawn, the spines must point backwards, lying in contact witli the cuticle 

 of tlie segment behind, each tract of intersegmental cuticle becoming 

 necessarily inverted and intervening between the segments respectively 

 before and behind it. 



