[NSECUTOR INSCITI^ MENSTRUUS 129 



Hay Gulch, Colorado, collected by Mr. D. E. Winchester. In 

 1908 I examined the Roan Mountains material without being 

 able to come to any definite conclusion as to the affinities of 

 these maggots, other than that they were probably muscoid. 



In 1916 Cockerell, in the Proceedings of the U. S. National 

 Museum, LI, 91-2, PI. 2, referred Musca ascarides to Hypo- 

 derma, gave additional details of its characters and figured it. 

 He examined additional material from the Green River shales 

 of eastern Utah. Credit is due him for first recognizing the 

 undoubted oestrid affinities of this maggot. I have now made a 

 careful study of the National Museum material, in the light 

 of Cockerell's findings, and am forced to the conclusion that 

 the form is markedly distinct from Hypoderma. The char- 

 acters of the new genus can be well set forth in the maggot 

 and puparium, and the genus may be advantageously recog- 

 nized at this time. 



Lithohypoderma, new genus. 



Genotype, Musca ascarides Scudder, 1877, Bull. U. S. Geol. 

 & Geogr. Surv. Terr., Ill, 756-7; and 1890, Tert. Ins. No. 

 Amer., 551. 



Differs from Hypoderma in the third-stage maggot possess- 

 ing six subcircular spinuliferous pads on dorsal surface of in- 

 termediate segments, arranged as follows : Two pads occupy 

 center of hind portion of segment, with two similar ones on 

 each side a little in advance of the central pair, the six dis- 

 posed in an irregular transverse band. These are figured by 

 Cockerell, but are more nearly circular than shown in his fig- 

 ure. In front of the central pair is a transversely elongate pad 

 bearing similar minute spines, which does not appear in Cocke- 

 rell's figure. The segments bear in addition narrow transverse 

 areas of small spines along hind margin, as in Hypoderma. 

 The small polished dorsal tubercles of Hypoderma, two in mid- 

 dle and one on each side of segment, appear to be absent. 

 Heavy short flattened spines with broad bases appear on the 

 anterior segments, as in Hypoderma. The anal stigmata are 

 of the same general plan as those of Hypoderma, but the sculp- 

 ture is finer, the button is smaller, and the lines radiating from 



