134 ILLINOIS BIOLOGICAL MONOGRAPHS [134 



meters: Length, 8, diameter of head, 0.28. Diameter of sucker, 0.08. 

 Segments not mature. One specimen August 28 ; length 14 mm. ' ' 



It is the writer's opinion that the folds of the neck are of no real 

 diagnostic value. Such folds may be seen on many other specimens of 

 cestodes in certain states of expansion and contraction. Unfortunately 

 Linton failed to figure or describe any of those internal structures which 

 are of real service to the modern systematist. His drawing of the ma- 

 ture proglottid is such that it cannot be interpreted but his drawings of 

 the head and of the last proglottids are of value for comparative pur- 

 poses. Linton himself believed that the segments of his species agreed 

 with Molin's description of T. hemisphaerica. Riggenbach (1896) con- 

 sidered Linton's T. dilatata to be identical specifically with T. hemis- 

 phaerica Molin. Nufer (1905) sought to show that these two species 

 were identical with Proteocephalus macrocephalus (Creplin). This may 

 prove to be the case but since the writer has not been able to study any 

 material of the T. hemisphaerica he has preferred to consider the latter 

 as a separate species. He is, however, ready to state that Linton's Tae- 

 nia dilatata is specifically identical with Proteocephalus macrocephalus 

 (Creplin). T. dilatata is therefore a synonym of the last named species 

 and it should be dropped from the list of valid names for Proteocepha- 

 lus species. Professor H. B. Ward very kindly secured for study Lin- 

 ton's slides and some alcoholic material of his Taenia dilatata. These 

 specimens, judging from the statements in his letter to Professor Ward, 

 must be from the lots described by Linton in 1889 and in 1901. Meas- 

 urements of the heads, suckers, proglottids and the cirrus-pouch, to- 

 gether with the general appearance of the worms, give ample reason for 

 considering this form to be identical with specimens taken from An- 

 guilla chrysypa, Lake Sebago, Maine, and which the writer is describing 

 as P. macrocephalus. These specimens agree in minute details of struc- 

 ture with the cestodes which Schneider (1905) described as P. macro- 

 cephalus. A more extended discussion of this comparison will be made 

 in the proper connection (Vide infra). 



Olsson (1893) reported specimens of cestodes from Anguilla vulga- 

 ris in Scandinavia. Riggenbach (1896) considered the form to be a 

 species of Ichthyotaenia. Stossich (1897:7) reported this species from 

 Anguilla vulgaris at Narenta, and again in a later paper (1898a :113-114) 

 he gave a short diagnosis of specimens taken from the same host species 

 at Trieste. In this diagnosis nothing of the inner anatomy of the worm 

 is given. His diagnosis reads : 



"Lunghezza 220 mm. ; larghezza 3.5 mm. Scolice in continuazione del collo, 

 allungato, ingressato al'innanzi, con grandi ventose globose, situate anteriormente ; 

 rostello cortissimo, ottuso, provveduto di una piccola ventosa apicale. Collo corto. 



