BREEDING BEHAVIOR OF SUCKERS AND MINNOWS. 25 



length by the following average percentages; anal and lower lobe 

 of caudal 31 per cent., pectoral 18 per cent., pelvic II per cent., 

 dorsal 5 per cent. 



6. Effective pearl organs occur in the male on the anal and 

 lower lobe of the caudal on the upper surface of pectorals, on 

 both surfaces of pelvics and dorsals and on the scales of the 

 sides behind the dorsal (Figs. I, 2, 3). 



7. The size of the pearl organs on the fins of the males is 

 roughly proportional to the percentage by which these fins 

 exceed in length the corresponding fins of the female. 



8. Females are without pearl organs. 



9. In the field males may be distinguished from females by 

 their coloration, by .their larger anal fins, by the possession of 

 pearl organs and by behavior. 



10. The smallest males and females observed breeding were 

 about six inches long. 



11. The males congregate on the rapids and the females 

 remain apart from them in the immediate neighborhood and 

 come to them one or a few at a time. 



1*2. When a female comes to a rapid she is pursued by two or 

 more males. 



13. The female intermittently flees from the males but finally 

 stops and permits their approach. 



14. The pairing is preceded by a characteristic tremor of the 

 head of the male and preceded or accompanied by a spreading of 

 the fins and a change in the color of the dark lateral stripe from 

 black to a brilliant red. 



15. The fins of the males are without conspicuous colors or 

 patterns; yet they are spread by the pairing males just as in 

 certain other species of teleosts in which the spreading displays 

 conspicuous colors or patterns. 



16. The female "pairs" with two males at one time (Figs. 2, 3). 



17. The two males may be of unequal size and both may be 

 smaller than the female. 



1 8. In the pairing position, one male lies on either side of the 

 female with his pectoral fin spread beneath her and his dorsal 

 elevated. The pearl organs of his sides and of his caudal and 

 anal fins are then in contact with the sides, caudal and anal of 

 the female (Figs. 2, 3). 



