8 ILLINOIS BIOLOGICAL MONOGRAPHS [358 



be accepted, that Andrya is the most primitive genus of the family, then 

 this becomes the most primitive known species. Its primitive characters 

 are (1) the very broad distribution of the testes which occupy nearly 

 the entire median field and part of the lateral ; ( 2 ) the fact that the 

 ovary is not nearer the pore side than the opposite side; and (3) the 

 limitation of the receptaculum seminis to the median field and its simple 

 globular character. In these characters this species is approached in 

 some respects by A. communis, next to be described, which must be 

 regarded as its nearest known ally. 



Andrya communis sp. nov. 

 [Figures 5-8] 



Professor R. T. Young collected in 1908 at Long's Peak, Colorado, 

 cestodes from Evotomys gapperi galei, Microtus pennsylvanicus modes- 

 tus and Peromyscus sp. They were examined by Hall who concluded 

 and reported (1912) that those from Evotomys and Microtus repre- 

 sented a species of Anoplocephala, while those from Peromyscus rep- 

 resented a second species of the same genus. Professor Ward has secured 

 for me the loan of this material for study. The cestodes from Pero- 

 myscus belong really in the genus Hymenolepis, except for one slide, 

 apparently mislabelled, which is of the same species as those from 

 Microtus. Those from Evotomys and Microtus prove to be two distinct 

 species, the first being an Andrya and the other probably an Andrya 

 also, tho the fragments at hand are all too far past sexual maturity 

 to allow of certain generic determination. The latter species must 

 therefore of necessity be omitted from consideration, tho it comes within 

 the scope of this paper. 



The species under consideration from Evotomys gapperi galei is 

 represented in the material at hand by about 200 fragments in alcohol 

 and 17 slides, most of which were prepared by Professor Young. Only 

 one scolex is in this lot, this being in the form of oblique cross sections. 

 Recently I have found in the collection of Professor Ward four frag- 

 ments, evidently representing one worm, which were of the same lot of 

 material, an:l were presented to Professor Ward several years ago by 

 Professor Young. This material includes a scolex with a considerable 

 number of proglottids attached, thus furnishing an idea of the appear- 

 ance of the complete worm. 



The total length is estimated to be about 3 or 4 cm ; the number of 

 proglottids, about 225. The greatest width is about 1.5 to 2 mm. The 

 proglottids vary in shape from 12 times as long as broad shortly before 



