238 BENEDICT. [Vol. XVI. 



I have not been able to obtain specimens of ambigiia, and 

 the literature which contains a more detailed description than 

 that of Dujardin is inaccessible. Hence I could not determine 

 from personal investigation whether ambigiia was a true type 

 of the genus which has been called Ichthyotaeriia. Riggenbach 

 ('96), however, lists ambigua as one of the IcJithyotaeniae, and the 

 excellence of his work on this group warrants me in accepting 

 this designation. The rules of priority in nomenclature, there- 

 fore, demand the adoption of the generic name Proteocephalus. 



The Getms Proteocephalus. 



The oldest literature on the ProteocepJiahis is found in the 

 works of Rudolphi ('10), Dujardin ('45), Diesing ('50), van 

 Beneden ('61), and von Linstow ('78). All of these authors 

 confine their descriptions to a few details concerning the 

 size and form of parts, particularly of the scolex and certain 

 proglottids. 



Zschokke ('84) was the first to make any study whatever of 

 anatomical structure, and therefore his work is of much greater 

 value than that of the older authors. The next author to make 

 an anatomical and histological study was von Linstow ('91), who 

 described T. longicollis. He was the first to note the relation- 

 ship between the various fish taeniae. In the following year 

 Kraemer ('92) made a very exhaustive study of Cyathocephahis 

 tnmcaUis, P. torulosa, and P.filicollis, and established the iden- 

 tity of P. filicollis and P. ocellata. He also pointed out other 

 common characteristics of the fish taeniae. Lonnberg ('94) was 

 the first to establish the group under the name IcJitJiyotaenia, 

 and made its characteristics still more distinct and accurate. 



By far the best work yet done on this group is found in the 

 paper by Riggenbach ('96), who, in addition to a careful descrip- 

 tion of two new species, has for the first time made an accurate 

 and discriminating summation of the present knowledge of this 

 group. At the present time a great amount of confusion exists 

 and the accuracy of the specific determinations is doubtful 

 in over half of the species of Ichthyotaenia so far described. 

 Riggenbach shows that out of a list of twenty-nine species 



