SPAWNING BEHAVIOR IN FUNDULUS HETEROCLITUS. 319 



burdened with their great masses of eggs, that must distend their 

 adbomens uncomfortably, and are eager to get rid of their bur- 

 dens. This can most easily be accomplished by contact with the 

 males, but may be and frequently is accomplished without the 

 latter. The females usually, however, retire to the bottom and 

 place themselves in contact with some solid object, sometimes 

 only the snout being actually in contact, thus assuming a posi- 

 tion in which they may be most readily clasped by the male. 

 Whenever a male sees a female in this position he loses no time 

 in spawning with her. If a female after taking up the position 

 just described is not joined by a male she is very apt to relieve 

 herself by assuming the S-shaped posture characteristic of the 

 spawning act and by vibrating her body just as she would if 

 clasped by the male. The eggs are thus plentifully extruded, 

 but if no males are present, they are not and probably never can 

 be fertilized. If, however, any males are in the vicinity they are 

 always attracted by the vibratory movement and dart toward the 

 source of vibration. 



Courtship, if such by courtesy it may be called, occurs shortly 

 before the sexual climax. Fish in this condition swim about com- 

 paratively quietly in pairs, the female above and the male just 

 below and slightly back of her. This position enables him to see 

 her more readily and at the same time to guide her about by 

 gently butting her on one side or the other with the top or sides 

 of his head. I have observed very many pairs swimming about 

 in this way for considerable periods of time. Gradually the male 

 becomes more excited in his movements and the prelinrnary 

 courtship merges into spawning behavior proper. At first the 

 attempts at spawning on the part of the male are apt to consist 

 merely of efforts to corner the female and to induce her to seek 

 some retired spot at or near the bottom. To accomplish this he 

 rises from beneath her and butts her downwards with the sides 

 of his head. If he succeeds in driving her into a suitable place 

 he attempts to spawn with her, the first few trials lacking the 

 vigor characteristic of ruling males. Sexual excitement increases 

 rapidly so that before many minutes have passed the male is apt 

 to be seen spawning promiscuously with any female that he en- 

 counters. This transition from courtship to spawning was ob- 



