379] ANOPLOCEPHALIDJE—DOUTHITT 29 



mens must have been composed of at least 225 proglottids, more 

 probably of 350 or 400 proglottids. 



The fact that Leidy's and Stiles' material were from the same 

 host, the only point that Cohn seems to have taken into consideration, 

 means nothing. I have taken 16 species of cestodes from Geomys, and 

 have not exhausted the field; Stiles (1896) has reported still another. 

 These species represent seven genera, and three families. The balance 

 of evidence seems to be in favor of Stiles' view that Leidy's species was 

 a species of the genus Davainea. 



Cohn criticise Stiles for the inadequateness of his description; but 

 with sectioned material before him he failed to add anything of impor- 

 tance to our knowledge. Incidentally he mentions that the female 

 glands are situated at a considerable distance from the median line, 

 which proves that he did not have before him Stiles' species but had 

 probably Schizotaenia variabilis, the next species discussed in this 

 paper. 



There were available for study specimens from Stiles' material 

 loaned by the Bureau of Animal industry; others were placed at Pro- 

 fessor Ward's disposal by Professor M. J. Elrod, the original collector 

 of the material; also, from the Bureau of Animal Industry a specimen 

 from a porcupine taken at Mayfield, Michigan. The first lot is from 

 Erethizon epixanthus, from Snake River, Wyoming; the second is from 

 Erethizon dorsatus. I have also specimens (No. 1502, B. A. I. Coll.) 

 identified by Stiles as this species; examination has shown that they 

 are distinct. 



External form (Stiles (1896) — "Strobila attains 33 mm. in length 

 by 6 mm. in breadth and contains about 90 segments, the oldest of 

 which are 8 mm. long. Head unarmed, measures 0.6 mm. broad by 0.38 

 mm. long by 0.32 mm. thick, and is nearly rectangular in apex view. 

 The neck is absent, and the head is frequently retracted in the body, 

 as in Drepanidotaenia lanceolata. Suckers round, 0.176 mm. in diame- 

 ter, open anteriorly". 



The genital organs alternate, in the specimens at hand, with per- 

 fect regularity from right to left. The genital anlagen are visible in the 

 first proglottid. The specimen from Mayfield, Mich., shows the 70th 

 proglottid still immature; apparently, maturity is reached about the 

 80th. No other specimen at hand gave information as to this point. 

 One must conclude from this condition, either that Elrod 's material 

 was all immature since it shows the total number of proglottids to be 

 about 90, or that the species is larger when inhabiting Erethizon dorsa- 

 tus. The latter conclusion seems more probable, since some of the 

 detached proglottids of the Elrod material are ripe. 



