1 8 JACOB REIGHARD. 



than two hundred in a well-developed specimen. On the sides 

 of the anal and caudal fins and on the tail for a little distance in ' 

 front of the caudal fin are large disc-shaped organs (not pointed). 

 Smaller, pointed organs occur on all the scales of the sides and 

 back, on the dorsal, on the upper surface of the pectoral and on 

 both surfaces of the pelvic. All these organs are effective in 

 proportion to their size. Here again the caudal and anal fins 

 of the male, which exceed those of the female by the largest 

 percentage, bear the largest and most effective pearl organs. It 

 is probable that further data would make possible a more precise 

 statement of the relation between size of pearls and relative size 

 of fins. 



This species is one of the few in which pearl organs have been 

 noted in the female. In a single specimen I have found minute 

 organs on the top of the head and on the first few scales of the 

 back behind the head. They were especially numerous about 

 the upper end of the opercular opening. They were too small to 

 be effective and care was needed to see them at all. 



3. Coloration. At 2:30 P.M. on May 17, 1904, I found ten 

 to tw r elve red-horse lying quiet in shallow water near the bank 

 of Mill Creek, near Ann Arbor. The water was smooth and I 

 was able to come within ten feet of them and watch them with 

 field glasses from an elevated position. The fish were from 

 twelve to fourteen inches long from tip of snout to tip of tail. 



The red-horse, seen at other seasons, whether in its native 

 waters or in aquaria, has the sides and back in both sexes uni- 

 formly olivaceous, but somewhat darker above. The belly is 

 smoky white. The sides show tinges of salmon in front of the 

 dorsals and the lower fins have some orange near the base. 



The red-horse before me were of such exceptional coloration 

 that they were at first not recognized. Pectorals, ventrals and 

 anals were bright salmon. Along the sides and running forward 

 above the eye was a white stripe similar to that of the white 

 sucker. It was more prominent in the darker colored individuals 

 but in none of them was a red stripe visible beneath it as in the 

 white sucker. In a few individuals infrequent, elongated white 

 spots were seen above the lateral stripe and running lengthwise 

 of the back. With field glasses pearl organs were visible on 



