a severely malformed ovary, the development of individual ova in 

 this gonad -vvas so retarded that the sex of the specimen could only 

 be determined with the aid of a microscope. A similarly malformed 

 and underdeveloped gonad was found in a male sea lamprey, 18.0 

 inches long (Traight: 152 grams). 



In the Carp Creek spavming run in 19hQ (2,938 specimens exam- 

 ined), 2 sea lampreys (female, 1^.0 inches, and male. 13.0 inches 

 in total length) were talcen which had deformed caudal fins. One 

 male, 11.0 inches long, had a disproportionately short body in 

 relation to its other structural features. T^to feraales were noted 

 each ivith a small, healed perforation in the anterior body wall. 

 In at least one of these cases the perforation opened into the body 

 ca\n.ty, their origin is not clear. 



It is concluded from these observations, that the migratory 

 populations of sea lampreys examined were quite perfect physically 

 and displayed no gross evidence of any maladjustment to their 

 relatively nevf habitat in the Lake Huron basin. These observations 

 agree, in general, mth those of Gage (1928) for the dwarf sea 

 lamprey (lalce lamprey) on its spawning grounds in inland New York 

 waters. Among these he noted only occasional instances of abnormal- 

 structure or development. 



(b) Parasitism 



During the 19U8 spawning runs, a random sample of 100 migrating 

 sea lampreys was carefully examined for the presence of internal 

 parasites. This sample was collected between June 2 and 8, 19U8, 

 in the Ocqueoc River falls (69 specimens) and in Carp Creek (31 

 specimens). Fifty-six of the sea lampreys were males ranging from 

 12.6 to 18.9 inches in total length (average: 16.6 inches) and Uh 

 were females ranging from 12.9 to 19.6 inches in total length 

 ( average : 16 . U inche s ) . 



Tirventy sea lampreys (10 males and 10 females) or 20 percent 

 of the total sample contained one or more indi"^n.duals of several 

 types of parasitic organisms iidthin their digestive tracts. The 

 most common of these were adults of the acanthocephalan, Echinorhynrlius 

 coregoni ^ -which occurred in 1? of the sea lampreys examined (9 males 

 and 8 females ) . With the exception of one sea lamprey which con- 

 tained three adult worms, all specimens examined had but one of these 

 parasites in the digestive tract. This parasite has commonly been 

 reported from triiitefish and various other northern fishes. 



«3^Identified by Dr. H. J. Van Cleave of the University of Illinoi: 



67 - 



