252 ILLINOIS BIOLOGICAL MONOGRAPHS [252 



for contraction and relaxation. Every head of the four lots was exam- 

 ined in this respect and in each sucker the lower margin was turned in 

 thus ** forming an angular intrusion into the cavity of the sucker" as 

 Smith (1908) described it. In the more contracted or in greatly ex- 

 panded suckers this condition was somewhat difficult to make out but 

 when properly cleared as in glycerine or balsam it was apparent. A 

 study of toto preparations of the proglottids from the various lots fails 

 to disclose any good characters for separating them. The writer 

 therefore bases the following description upon this material so collected 

 together, referring at times to special lots. He also uses the descriptions 

 by Smith (1908) and by Monticelli (1899) as sources of comparative 

 data. It was desired to study the slides upon which Monticelli based 

 his description but unfortunately Professor Ward was unable to secure 

 them. 



This is one of the largest of the Proteocephalid species inhabiting 

 snakes. 0. calmettei (Barrois), 0. marenzelleri (Parona), 0. grandis are 

 of about the same size. The latter even exceeds C. gerrardii in some 

 measurements. Next smaller than the members of this group comes 

 0. racemosa (Rud.). A comparison of the table at the end of this 

 report shows the size relationships of these species. The strobila varies 

 considerably in length. According to Baird (1860) it measures 45.6 

 cm. (18 inches). Smith (1908) reports specimens 95-100 mm. long. 

 Diesing (1850:511) gives its length as 2 inches to 11/^ feet. Monticelli 

 gives no data on this point. The reported breadth varies from 0.85 

 mm. in some short specimens examined by the writer to 1.8 mm. in the 

 B. A. I. slide 1858, to 2.0 mm. according to Smith, and 2.0-6.0 mm. 

 (1-3 lines) in the middle to 2 mm. (1 line) at the posterior end, accord- 

 ing to Diesing (1850). The strobila is flat and relatively thin. The 

 surface is more or less thrown into folds. The proglottids are attached 

 by their full width. The segmentation is indistinct in the anterior 

 region and more distinct in the region of mature and ripe proglottids. 

 In certain strobilas the segmentation is more distinct than in others. 

 It is never as clearly marked as in some species of Proteocephalids. 



The head is large, readily distinguishable to the naked eye. Baird 

 describes it in these words: "The head is large, tetragonal; the four 

 bothria disposed crosswise, joined by the margins." Smith (1908) says 

 of it, "The head, viewed from the front presents a crucial appearance 

 from the prominence of the suckers, measuring transversely across the 

 two opposed suckers 1.5 mm. and laterally across two adjacent suckers 



1.3 mm The suckers, thus prominent, form the rounded arms 



of the crucial frontal picture, each sucker being globose in shape and 

 having a lateral diameter of about 0.7 mm." Smith's figures of the 



