399] ANOPLOCEPHALIDJE—DOUTHITT 49 



variabilis (page 22). Bowie, Maryland, and Blair, Oklahoma, are in the 

 Upper Austral faunal zone, while Seven Lakes, Colorado, is in the 

 Boreal. 



The Colorado forms may deserve the rank of a separate variety, 

 on account of the difference in stage of sexual maturity ; but until the 

 character has been determined for more than two or three individuals 

 on each side, such a step would not be justified. Variations of far 

 greater import have been recorded in this paper which were found in 

 individuals of the same species and from the same host, and even in 

 different proglottids of the same individual. The name, Cittotaenia 

 mosaica, should therefore be dropped, and the excellent description by 

 Hall (1908) applied to C. perplexa, the only change necessary being to 

 recognize that sexual maturity may not occur until the 95th proglottid 

 and that in addition to occurring in Sylvilagus pinetis of Colorado it 

 also occurs in Sylvilagus floridanus of Maryland and Oklahoma. There 

 seems no reason to doubt that the testes are sometimes separated into 

 two groups, as described by Stiles. 



C. pectinata and C. perplexa are strikingly similar in several 

 unique characters, and it seems not improbable that their differences 

 may be due to environmental conditions, since one is a parasite in the 

 cottontail and the other in the jack rabbit; but my present opinion is 

 that such a decision would be premature, without testing it by breeding 

 experiments. C. perplexa differs from C. pectinata in the following 

 points, all of which are quantitative : 



1. The testes are fewer 



2. The cirrus pouch is smaller 



3. There is a more complicated network of excretory ducts in the 

 lateral portions of the median field 



4. The ovary is smaller 



THE GENUS CITTOTAENIA 



Zschokke in 1907 described a cestode from Phascolomys wombat, 

 giving it the name Moniezia diaphana. His excellent description how- 

 ever seems to be that of a perfectly normal Cittotaenia, and disagrees 

 with Moniezia on every point in which these two genera differ. The 

 species is here transferred to the genus Cittotaenia for the following 

 reasons : 



1. The vagina is not ventral on the right and dorsal on the left, 

 as in Moniezia. 



2. There are no shields on the ends of the horns of the pyriform 

 body. 



