22 JACOB REIGHARD. 



caudal they are somewhat smaller, still smaller on the sides of 

 the tail. Those on the anal are distinctly perceptible to touch, 

 those on the caudal and sides of the tail are barely perceptible 

 while the rest are quite imperceptible. Probably only those on 

 the anal are in any degree effective and they are not sharp. It is 

 evident that neither the coloration, the length of the fins, nor 

 the pearl organs afford means of discriminating the sexes in the 

 field. For this purpose one is compelled to rely on the difference 

 in average size and in behavior. 



3. Breeding Activities.- I have several times seen a single large 

 hogsucker moving upstream in rapids and accompanied or fol- 

 lowed by three or four smaller. In one case the large fish was 

 some twelve inches long and the four following her half as long. 

 Occasionally she stopped and one of the smaller fish placed 

 himself by her side. But nothing further occurred and the fish 

 presently moved on. 



My only opportunity to observe the actual spawning of this 

 species was on May 4, 1904, in Mill Creek, near Ann Arbor, at 

 the point at which the spawning of the red-horse had been already 

 seen. I was watching the rapids about 4:30 P.M. when a large 

 hogsucker came upstream followed at a short distance by half a 

 dozen others of two thirds her length. Size and behavior indi- 

 cated the larger fish in this and other cases to be a female. 

 Presently she stopped and remained quiet on the bottom while 

 the males pressed against her three on either side, so close as to 

 hide every part of her except the head and tip of the caudal fin 

 (Fig. 7). The seven fish remained together for several seconds 

 and during this time the female several times made rapidly re- 

 peated movements of protrusion and retraction of the mouth. 

 She was not seen to make any other movement nor was any 

 seen in the males. After remaining thus grouped for a fraction 

 of a minute the fish moved on, the female leading. Two some- 

 what larger males now approached and when the female again 

 stopped these added themselves to the other six, so that the 

 eight of them formed a complete mantle over her back and 

 sides from which only her head and caudal projected. Again the 

 female was seen several times to make rapidly repeated move- 

 ments of the mouth. The fish then passed out of sight on their 

 way upstream, the female still leading. 



