Volume II. October, l8g8. Number 2. 



ZOOLOGICAL BULLETIN. 



OBSERVATIONS ON THE ANATOMY OF A SPECIES 



OF PLATYASPIS FOUND PARASITIC ON THE 



UNIONIDAE OF LAKE CHAUTAUQUA. 



HENRY LESLIE OSBORN. 



The facts recorded in this article were gathered partly on 

 living material at Chautauqua, New York, in the Biological 

 Laboratory of Chautauqua College of Liberal Arts, and chiefly 

 in the Biological Laboratory of Hamline University, St. Paul, 

 Minn. The fluke was first noticed in July, 1895, in speci- 

 mens of Anodonta which were being used in class work. A 

 few drawings were made at the time, but no attempt at identi- 

 fication could be undertaken then, as the necessary books were 

 not at hand. Later in the year I consulted Bronn's Klassen 

 und Ordmmgen and decided that it could not possibly be 

 regarded as the usual parasite of the Uniojiidae Aspidogaster 

 coiichicola, and recognized that it bore a remarkably close 

 superficial resemblance to a species designated in that work 

 as the Aspidogaster lenoiri of Poirier ('85). Such points as 

 could be determined by a mere surface study of the animal 

 indicated clearly a very decided likeness between Poirier's spe- 

 cies and mine, but the point which made me hesitate in asso- 

 ciating them at that time was the fact that Poirier's animal 

 is only recorded from a single region, viz., Senegal, Africa, 

 and from a single host, Teti^atJiyra vaillanti, a cJielonian. 

 Unfamiliarity with the Trematoda and pressure of other work 

 prevented me from investigating the case at that time, and 

 I did not really take it in hand till the fall of 1897, when 

 I was gathering the facts for a paper, Osborn ('98), on the dis- 



