DISCOVERY OF THE GREAT LAKE TROUT, 



CRISTIVOMER NAMAYCUSH, IN THE 



PLEISTOCENE OF WISCONSIN 



L. HUSSAKOF 



American Museum of Natural History, New York 



Some fish remains consisting of a portion of a skull and a num- 

 ber of associated elements, from an interglacial clay deposit in 

 Dunn County, Wisconsin, were recently sent to me for identification 

 by Dr. S. Weidman, of the State Geological Survey of Wisconsin. 

 They turned out to be remains of the great lake trout, Cristivomer 

 namaycush, a species now living in Wisconsin waters. They are 

 therefore of interest as carrying back the history of this species to 

 Pleistocene times. Through the kindness of Dr. Weidman, I am 

 permitted to present the following notes on the specimens. 



The remains consist of a portion of a skull of a fish about two 

 feet in length, with most of the jaw elements belonging to it, and 

 a number of thin and more or less fragmentary bones pertaining 

 to the opercular and hyoid series. Associated with these remains 

 was a toothed fragment of the jaw of another species of fish, as yet 

 undetermined. 



The genus Cristivomer is distinguished from all other trouts 

 and salmons (family Salmonidae), by the shape of the vomer. 

 This element, in side view, and held with the oral face up, is boat- 

 shaped, with a raised crest armed with strong teeth, extending 

 in the median line of the oral face, from the head of the bone back- 

 ward (Fig. ib). By this element alone the remains are identi- 

 fiable as belonging to genus Cristivomer; and all doubt whatsoever 

 is removed on comparing the other bones with a disarticulated 

 skull of the living lake trout. The correspondence bone for bone 

 is very close, extending to details, so that the fossil form cannot 

 be separated even as a variety from the existing one. 



No detailed discussion of the several elements seems necessary; 

 reference may be made to Fig. i, in which the better preserved 



68 S 



