Naclidriirk verbot rn . 

 UehvrftrtziiiKiürechl voihclmltni. 



Cotylogaster occidentalis n. sp. 



and a Revision of the Family Aspiclobothridae. 



By 

 W. S. ^'ickerson. 



With Plates 32 and 33 and 1 figure in the text. 



The subject of the present paper is a previously unknown re- 

 presentative of the Trematode family Aspidohothridae found living iu 

 the Mississippi Valley. It resembles Cotylogaster michaelis Mont. 

 more closely than any other from which is known aud I have there- 

 fore described it in a preliminary notice (Nickerson '99) as a member 

 of that genus giving it the specific narae occidentalis. The new form 

 was discovered duriag the summer of 1899 while upon the house-boat 

 "Megalops" which was maintained by the Minnesota Natural History 

 Survey upon the Minnesota and Mississippi Rivers for the investigation 

 of their fauna. It occurs parasitic in the intestine of the "Sheeps- 

 head" Aplodinotus grunniens Raf. though by no means abundantly. 

 I found 7 specimens in the intestine of one fish taken from the 

 Minnesota River near Jordan. I have since examined a considerable 

 number of other sheepsheads in the hope of finding more Cotylogasters 

 but without success. 



One of the 7 specimens was killed (HgClg) while flattened in the 

 compressor and subsequeutly stained and mounted as an entire pre- 

 paration. This has been of great service in tracing the anatomical 

 relations of the organs as represented in the diagram (Fig. 15). Two 

 of the other 6 specimens were made into serial sectious, one series 

 transverse and one sagittal, two were accidentally lost by the eva- 

 poration of the alcohol in which they were preserved and the remain- 

 ing two are deposited as type specimens in the Zoological Museum of 

 the üniversity of Minnesota. 



