96 Seal — Breeding Habits of Viviparous Fishes. 



The female Heterandria is at least double the bulk of a male 

 Gambusia, though not of much greater length, and much more 

 than a match for him. In the attacks of the females of either 

 species they seem to endeavor to bite the long slender organ of 

 the male, which is no doubt the most vulnerable point. 



This pair were together for two summers and the production 

 of young throughout was approximately the same as that of the 

 pair of Heterandria previously mentioned. 



Notwithstanding the viciousness displayed by the females 

 with apparently no sign of yielding, there may be a cessation 

 of hostilities during the darkness of night as they appear much 

 more quiet in a dim light. There may be times also when there 

 is a yielding from sexual impulse, but I have never been able 

 to observe it. This is probable and would be analogous to the 

 conduct of higher animals. 



The male generative organ, as may be seen by the accom- 

 panying figures, is extremely long in proportion, being almost 

 a third as long as the fish. It can be thrown completely in a 

 circle close against the body of the fish as though working on 

 a pivot. 



