No. 4-] IDENTITY OF COTYLASPIS. I S3 



and not a larval stage of Aspidogastcr concJiicola, with which, as 

 Leidy ('57, '58) reported, it is associated. I have found the eggs, 

 the young in various stages, and the adults of Cotjlaspis, but no 

 trace of any evidence to support the conjectures of Leidy ('58) 

 and Monticelli ('92) that Cotjlaspis is one stage in the life cycle 

 of Aspidogaster. The doubt raised by Leidy ('58) and amplified 

 by Monticelli ('92) is thus removed, and the species as originally 

 described by Leidy ('57) should be recognized. Furthermore, 

 the ectoparasitic habit, the presence of eyes, and the presence, 

 on the adult, of a ventral sucker containing a definite number 

 of alveoli necessitate, to my mind, the rehabilitation of the 

 genus Cotylaspis to receive this species. As Stafford ('96) has 

 shown, a variable number of alveoli, may be present in the 

 ventral sucker of Aspidogaster when sexually mature. 



The eyes of Cotylaspis insignis are very prominent in the 

 adult, and their nervous connection with the cerebral mass can 

 readily be demonstrated with methylen blue. Osborn's state- 

 ment that in trematodes eyes "are not hitherto recorded of 

 adults" is not strictly correct, since Braun, for example ('89-'93, 

 pp. 464, 465, and 693), cites no less than fourteen different 

 genera of the Monogenea, and one of the Digenea, in which 

 species occur whose adults have well-defined eyes. 



Cotylaspis insignis is also peculiar in possessing, as does 

 Aspidogaster, a series of so-called marginal sense organs, placed 

 in the angles of the crenulate margin of the ventral sucker at 

 the points where the partitions between the alveoli of the outer 

 circle meet the outer wall. There are thus twenty of these 

 peculiar organs in Cotylaspis insignis. Neither Leidy ('57, '58) 

 nor Osborn ('98) mention these organs; they are, however, 

 present in a specimen kindly loaned to me by the latter for com- 

 parison. The genus Platyaspis, as defined by Monticelli ('92) 

 for the reception of Poirer's African species, has for one of its 

 diagnostic characters the absence of these marginal sense 

 organs. Poirer, however, in his original description makes 

 no statement as to the presence or absence of these organs, and 

 Monticelli ('92) and Braun ('89, '93) have taken this negative 

 evidence as a warrant for their statement that the organs in 

 question are absent. The points of contrast between the two 



