176 ILLINOIS BIOLOGICAL MONOGRAPHS [176 



ovidotto ravvolto in ambagi e ripieno di uova sferiche. Nel mezzo vidi collocato 

 orizontalmente il membro virile attortigliato che si estendeva fino al centro dell' 

 articolo. 



"OSSERVAZIONE 3. Fino ad ora non si conosceva dell' anguilla altro che 

 la Taenia macro cephala, dalla quale pero la hemisphaerica si distingue per la forma 

 della testa non che per la lunghezza del collo. Questa e affine alia filicollis, dalla 

 quale pero si distingue per la forma della testa e del collo, e deve percio venir 

 registrata dopo di questa nel sistema." 



Since the appearance of Molin's paper no further attempts have 

 been made to describe this species. There is in fact no further notice 

 of the finding of this species. Linton (1886) thought that his Taenia 

 dilatata might be the same as Taenia hemispherica. Riggenbach (1896) 

 said of it, "Ein genauer Vergleich der Diagnosen, welche die genannten 

 Autoren den fraglichen Species gaben, zwingt mich mit Bestimmtheit 

 eine Identitat der /. (Ichthyotaenia) dilatata Linton mit /. hemispher- 

 ica Molin anzunehmen." Linton's species has been determined by the 

 writer to be identical with Proteocephalus macrocephalus (Creplin). 

 Schneider (1903) identified a cestode taken from Anguilla vulgaris as 

 Ichthyotaenia hemispherica. Later (1905) he decided that this form 

 was not I. hemispherica but I. macrocephala (Creplin). His statement 

 of this is discussed in the historical summary of Proteocephalus macro- 

 cephalus. Nufer (1905) attempted to show the identity of P. dilatatus 

 (Linton) and P. hemisphaericus (Molin) and further that these species 

 were identical with P. macrocephalus (Creplin). This contention is 

 true in part at least. In the discussion of P. macrocephalus in another 

 part of this monograph identity of P. dilatatus and P. macrocephalus 

 has been shown. The present form, however, is so little known and so 

 poorly described that it seems advisable for the present to consider that 

 it is not identical with the well known species of Proteocephalus found 

 in Anguilla but that it is a species inquirenda. La Rue (1911:475) 

 listed this form among other species of Proteocephalus. 



