56 OSBORN. [Vol. II. 



coloration of Anodonta shells by a distomid parasite. I planned 

 then to append the facts about Platyaspis to that paper in a 

 short note. But as soon as I looked into the case I found a 

 number of interesting points whose novel character made it 

 necessary to present the evidences in the case in a way impos- 

 sible in a mere note, and hence I withheld the matter and have 

 made it the subject of another article. Poirier referred the 

 animal which he discovered to the genus Aspidogaster, and 

 Braun ('92) in Bronn's Klasseti tind Ordniingcn followed his 

 assignment of the animal to that genus. But Monticelli ('92), 

 in his revision of the Aspidobothridae which accompanies the 

 paper on Cotylaspis in Leukart's Festschrift, showed that Poi- 

 rier' s animal cannot be regarded as an Aspidogaster, and erected 

 for it the genus Platyaspis, of which it has thus far been the 

 solitary species. So far as I have been able to ascertain, Platy- 

 aspis has never been recognized, excepting from the one locality 

 in which Poirier found and described it. It is, consequently, 

 an interesting and remarkable fact that it should occur in this 

 country and in a very different host, and a fact which should 

 not be presented without a sufficiently detailed account of the 

 evidence to compel belief in the correctness of the observation. 



I have not been able to decide in my own mind whether the 

 Chautauqua animal is specifically distinct from the African 

 species or not. This is partly because I have not as yet had 

 access to the original descriptions of Poirier, and do not know 

 how absolutely exact his account and the reports of them are. 

 The Chautauqua animal is slightly different from his, but not 

 more so than might be consistent with membership in the same 

 species. In case the Chautauqua animal proves to be distinct, 

 I shall propose for it the name Platyaspis anodontae, and for 

 convenience shall so term it in this article. 



The facts which are contributed in this paper are derived 

 from studies of preserved material made in the Biological Lab- 

 oratory of Hamline University. At the time of their discovery 

 I made sketches of the living animals, but did not attempt to 

 study them in detail. Last summer I preserved a few by drop- 

 ping them into cold saturated aqueous corrosive sublimate solu- 

 tion. The material has its limitations, but is sufficiently well 



