24 JACOB REIGHARD. 



Although the absence of the vibratory movements character- 

 istic of spawning suggests that the fish whose behavior is de- 

 scribed did not actually spawn, the attitudes can be no other 

 than those of spawning fish. These attitudes can be the more 

 readily maintained owing to the general distribution of pearl 

 organs over the surfaces of both sexes. Not only is the occurrence 

 of these organs on the female exceptional, but their distribution 

 in the male is unusual in that they are found on the lower surfaces 

 of the pectoral fins. Males which are above the female presumably 

 have the lower surfaces of the pectorals in contact with her back 

 and sides while those at the sides of the female have the upper 

 surfaces of their pectorals in contact with her belly. 



Assuming that the spawning behavior was observed it differs 

 from that of the white sucker in the following particulars, 

 (i) The act is not preceded by change of color; the fish show the 

 same color characters as at other seasons. (2) The act was 

 participated in by more than two males. If it be objected that 

 all but two of the males present were supernumerary, and that 

 the spawning was aborted by their presence as in the case of the 

 white sucker, it may be replied that the fish remained in position 

 long enough to spawn and that those above maintained their 

 positions quietly and did not attempt to displace those below. 

 The whole appearance was that of spawning except for the 

 single feature of lack of vibration. 



SUMMARY OF OBSERVATIONS. 

 A. The White Slicker (Catostomus commersonii). 



1. The white sucker breeds in southern Michigan in April 

 and early May. 



2. The fish then congregate in the shallow swift water of small 

 streams where the bottom is gravel and sand. 



3. At this time both males and females have a yellow-white 

 occipito-lateral stripe not known to occur at other seasons. 



4. This stripe is whiter in males than in females and below 

 it on the sides males have a dark lateral stripe often of rosy tinge. 

 The backs of males are often flecked with white not observed in 

 females. 



5. The fins of the males exceed those of females of equal 



