SPAWNING BEHAVIOR IN FUNDULUS HETEROCLITUS. 337 



nine females of the species Cyprinodon variegatus were introduced. 

 At about eight o'clock in the morning, when all was quiet in the 

 room I had a fine opportunity of observing the spawning behavior 

 of these fish. Of the five males three were in spawning plumage, 

 one of them being noticeably more brilliant than the other two. 

 When I first observed these fish this brightest male had acquired 

 complete control of the situation. He was so extremely active 

 and pugnacious that he succeeded in driving not only the other 

 males but the females into the friendly shelter of the masses of 

 coarse brown seaweed. Whenever any of the other fish so much 

 as ventured to poke its head out of the shelter the ruling male 

 would dash up and scare it into its retreat again. One of the 

 brighter males, less subdued than the rest, ventured out more 

 frequently and farther than the others. Instead of meekly retiring 

 before the vigorous onslaught of the enemy, he offered consider- 

 able resistance. On several occasions the encounters between 

 the two males developed into combats at close quarters, in which 

 heads and jaws were the weapons. They would begin by butting 

 heads fiercely and would occasionally grasp jaws and shake one 

 another powerfully from side to side as though each were en- 

 deavoring to tear out his opponent's jaw. These struggles were 

 usually short lived, one of the belligerents, invariably the one that 

 had been in hiding, seemed to tire. They would then separate, 

 as though by mutual consent, and the defeated male would in- 

 gloriously retreat to shelter, usually slowly as though exhausted. 

 I have been unable to notice that either of the combatants in 

 these frays receive any injury. 



It is, I believe, more of a test of vigor and endurance than any 

 attempt to inflict bodily injury. On the supposition, then, that 

 sexual vigor and general bodily vigor run parallel and that the 

 index of both is the brilliancy of coloration, we can readily under- 

 stand why it is that the most brilliantly colored male is invariably 

 the victor in these struggles for supremacy. It probably is the 

 case too that a higher courage accompanies a higher bodily and 

 sexual tone and makes a male at his climax practically invincible. 

 It seemed to me, as I watched the activities of this male, that his 

 extreme impetuosity was decidedly a detriment to him, for he 

 defeated his own ends by driving away all females that ventured 



