100 ILLINOIS BIOLOGICAL MONOGRAPHS [100 



(1892) and as an illustration of the proglottid of the species he appar- 

 ently redrew Kraemer's figure 18. Apparently also he either ignored 

 Schneider's work or else he considered Kraemer's T. ocellata and 

 Schneider's Ichthyotaenia percae to be identical without having made a 

 comparison of the material. No one who has made a careful comparison 

 of Schneider's and Kraemer's drawings and descriptions would think 

 of putting them in the same species. It has been shown elsewhere in 

 this monograph that Kraemer's T. ocellata, or T. filicollis as he called 

 his species in one part of his paper, is not the same as Schneider's 

 Ichthyotaenia percae. Kraemer's specimens doubtless belong to Proteo- 

 cephalus fallax La Rue. 



A comparison of Muller's (1780 and 1788) data and drawings of 

 Taenia percae with Rudolphi's (1802a and 1810) diagnoses and descrip- 

 tions of Taenia ocellata compels the writer to believe that they were 

 referring to the same form. It is also to be remembered that Rudolphi 

 gave Muller's Taenia percae as a synonym of his own T. ocellata. There 

 remains no reason why the name which Miiller suggested for this species 

 should not be used instead of the name suggested by Rudolphi many 

 years later. The generic name is Proteocephalus. Attention is called 

 to the fact that Muller's figure 1 (reproduced Fig. 173) compares very 

 favorably with Schneider's figures and with his specimens which the 

 writer has examined. Muller's figure 4 (reproduced Fig. 172) shows 

 the shape of the proglottids and the location of the genital organs very 

 well. The light area extending from the margin nearly to the middle 

 of the segment is doubtless the cirrus-pouch which under certain cir- 

 cumstances could have been observed by Miiller. Muller's figures 2 and 

 3 of the heads (reproduced Fig. 121, 122) are much like the heads of 

 Schneider's specimens which the writer has examined. Taken all in 

 all the identification seems to be as complete as is possible without a 

 study of Muller's and Rudolphi's actual specimens. 



Since the time of Rudolphi the specific names Taenia filicollis and 

 T. ocellata have appeared frequently in the literature of helminthology. 

 For the most part the names are listed in reports of parasites found, 

 without diagnosis and without description. In such eases the identity 

 of the forms so named can not be determined with any degree of 

 accuracy. A consideration of the host can at times throw a little light 

 on the subject but this datum alone is not to be trusted. It is noteworthy 

 that in the case of Taenia filicollis no author prior to Zschokke claimed 

 to find this species in any other than the sticklebacks, and, indeed, in 

 only two species of sticklebacks. Zschokke (1884) reported this species 

 from a number of hosts, none of them sticklebacks. In the case of 

 Taenia ocellata no author prior to Zschokke reported this species in any 



