424 Simon Henry Gage 



According to all zoologists the lampreys (Petroniyzontidae) 

 are very low in the zoological scale, and according to manj^ 

 they are degraded forms. They are found in the temperate 

 regions of both the northern and southern hemispheres ; and 

 all, so far as investigated, lay their eggs in fresh water and 

 pass their larval life there. Some pass their entire life in fresh 

 water while others go down to the sea, but all finally, on the 

 attainment of sexual maturity, once more ascend the streams 

 to their birth-place where the eggs for a new generation are 

 deposited, thus completing the life cycle. 



Both the lake and the brook lamprey agree entirely with 

 the designation for the Petroniyzontidae as given above, and 

 besides the lake lamprey agrees with the characters given for 

 the genus Petromyzon, viz. : The supraoral lamina, or maxil- 

 lary tooth-plate, is contracted and with two cusps placed 

 close together ; infraoral lamina or maxillary tooth-plate with 

 six to nine cusps. The discal teeth are in concentric series ; 

 those on each side of the mouth are bicuspid. (PI VI). 



With reference to the specific relationship of the large lake 

 lamprey there has been considerable diversity of opinion. 

 Up to the year 1875, the University had only secured small 

 lampreys caught on fish, none of them exceeding 15 to 20 

 centimeters. The coloration of these lampreys was white on 

 the ventral half and nearly uniformly black, or bluish black 

 along the dorsal half of the body. In the spring of 1875, 

 however, there was obtained from Cascadilla Creek, near the 

 University, a specimen nearly twice as large as the ones 

 usually obtained and with a strikingly different general ap- 

 pearance, due in part to the greater size and more variegated 

 coloration, but mostly to a large rope-like ridge extending 

 along the back from the gills to the dorsal fin. The two dor- 

 sal fins were continuous, simply having a depression between 

 them. The specimen was photographed when fresh and is re- 

 produced in PI. Ill, fig. 5. The general appearance, so 

 strikingly unlike either the small lake lampreys previously 

 obtained or the specimens of true sea lampreys in the museum, 

 seemed to indicate that, responding to its special lacustrine 

 environment this lamprey had assumed characters which 



