122 BIOLOGICAL LECTURES. 



The general color of C. agassizii is light gray. The scales 

 are lighter than the area surrounding them. 



The color pattern is more striking than in the other species 

 of the genus. Each somite is bordered by a dark line. The 

 lines of successive somites are separated by an almost imper- 

 ceptible colorless line. A broad, not sharply defined, band 

 extends along the sides. The middle of this is lighter than 

 the margin. Another one extends between the somites and 

 the ventral musculature, another from the nape between the 

 lateral somites and the dorsal muscles, and a diverging one from 

 near the nape to either side of the dorsal fin. Dark areas are 

 found along either side of the dorsal and anal fins. These areas 

 are caused by the accumulation of pigment along the borders 

 of the small muscles of the fins. Still another dark area is 

 found about the caudal. The ventral surface is white, except 

 the accumulation of pigment along the lines separating the 

 muscles. 



The fins are uniformly light gray. A light area is found on 

 both the upper and lower part of the caudal peduncle, just 

 within the first short rays of the caudal. 



The general color of Typhlichthys is cream and pink. It is 

 abundantly pigmented. In younger specimens the pigment 

 is arranged in definite areas about the head. In the old it 

 is more uniformly distributed, being, however, specially abun- 

 dant about the brain. The pigment pattern of the body is pre- 

 cisely as in Chologaster, except that the individual pigment 

 cells are minute and their aggregate not evident except under 

 the lens. 



The retention of the color pattern of Chologaster in Typhlich- 

 thys is not less interesting than the retention of similar habits. 

 It is perhaps due to different causes. The color pattern in 

 Chologaster is determined by the underlying muscular struc- 

 ture, and the retention of a similar pattern in Typhlichthys is 

 due to the same underlying structure, rather than to the direct 

 hereditary transmission of the color pattern. 



In Amblyopsis the color is much less marked than in Typh- 

 lichthys. They are flesh-colored, ranging to purple in the gill 

 region, where the blood of the gills can be seen through the 



