THE BLIND FISHES OF NORTH AMERICA. 



>S 



year. The eggs are large — 2.3 millimetres in diameter from mem- 

 brane to membrane — and about sixty to seventy are laid at one 

 time. 



Certain structures gain an entirely new significance in tbe light 

 of the breeding habits. These are the enlarged gill cavities, with 

 the small gills, the closely applied branchiostegal membrane, and 

 the position of the anus and sexual orifices. The latter are placed 

 just behind the gill membrane in such close proximity to it that 

 they can be covered by it. It is probable, therefore, that the 

 membrane is drawn over the sexual orifice and the eggs deposited 

 directly into the gill cavity. In an individual thirty-five milli- 



Fio. 16.— The embryo of TypUogohim, showing the well-developed eye. 



Fig. 17. — A yoimg Typhlogolius, times 4%- 



Fig. 18. — Adult Typhhgohius. 



Fig. 19.— Adult GilUchthys-y-caiida living in crab holes in San Diego Bay. 



Fig. 20.— Young GilUcTithys mirabilis under the same magnification as Fig. 17. 



metres long the anus is situated between the origin of the pec- 

 torals; in one twenty-five millimetres long it lies between the pec- 

 torals and ventrals. In the young it lies behind the ventrals, as in 

 other fishes. 



In an aquarium containing six Amblyopsis two took a great 

 antipathy to each other. Whenever they touched, a vigorous con- 

 test began. Frequently they came to have a position with broad- 

 side to broadside, their heads pointing in opposite directions. At 

 such a time the fight consists in quick lateral thrusts toward 

 the antagonist to seize him with the mouth. The motion is in- 

 stantly parried by a similar move by the antagonist. This blind 

 punching may be kept up for a few seconds, when, by their vig- 

 orous motions, they lose each other and jerk themselves through 



