1 82 KOFOID. [Vol. II. 



disposition of the species by the doubt expressed by Leidy, and 

 expanding the original describer's suggestion into a statement 

 that Cotylaspis insignis may be the young of Aspidogaster. 

 Inasmuch, however, as the species described by Leidy had eyes, 

 and the young of A. coticJiicola, as described by Aubert ('55) 

 and by Voeltzkow ('88), are not provided with these organs, 

 Monticelli further suggests that the form found by Leidy in the 

 pericardium of clams upon which Cotylaspis insignis was para- 

 sitic, and reported by him ('57, '58) as Aspidogaster conchicola, 

 may not have been that species but another — by inference un- 

 described — American species of Aspidogaster. Braun ('89-93) 

 follows Monticelli ('92) in assigning Poirer's species lejioiri to 

 the genus Platyaspis, though in the explanation of Figs, i and 

 2, Taf. XX, he refers to the species as Aspidogaster lenoiri. 

 Because of this double designation Prof. H. L. Osborn's ('98) 

 statement that " Braun ('92) in Bronn's Klassen 7md Oi'dnungen 

 followed his [Poirer's] assignment of the animal to that 

 genus " {Aspidogaster) is correct only for the plate designation) 

 Braun also follows Monticelli in assigning Cotylaspis ifisignis 

 to the genus Aspidogaster, but admits it to the list of valid 

 species. He also cites Leidy's paper of 1857, but quotes 

 (p. 896) his description of 1858. 



Professor Osborn ('98) has recently described as Platyaspis 

 anodontae a trematode which he has found on Anodonta (species 

 not given) and Unio liiteolns from Lake Chautauqua. This is, 

 I believe, unquestionably Leidy's Cotylaspis insignis. Unfortu- 

 nately, Professor Osborn does not discuss the relationship of 

 the form which he has described as new, to the species found 

 by Leidy, and does not even mention the genus Cotylaspis 

 except when, by a curious lapsus pennae, he substitutes Coty- 

 laspis for Cotylogaster in his reference (p. 56) to Monticelli's 

 "paper on Cotylaspis in Leuckart's Festschrift!' I fail to see 

 in Professor Osborn's more extended account any disagreement 

 with Leidy's original description, and a comparison of specimens 

 shows that he is dealing with the same form that occurs at 

 Havana, which I have referred to Leidy's Cotylaspis. From Pro- 

 fessor Osborn's account of the animal and my own observations 

 it follows that Cotylaspis insignis is a sexually mature animal 



