268 FISHES. 



The smaller Hybopses and Hemitremioe, scarcely reach a 

 length of two inches. 



The spring or breeding dress in many genera is 

 peculiar. Often the top of the head, and sometimes the 

 whole dorsal region also, is covered in the males with 

 rows of spinous tubercles, outgrowths from the epider- 

 mis, and usually the skin of the muzzle is then swollen 

 and charged with pigment. In Semotilus and Ceratich- 

 thys these tubercles are quite large and cover the front 

 and sides of the head; in Pimephales and Hyborhynchus 

 they are placed entirely on the front of the obtuse snout; 

 in Campostoma the whole dorsal region, and sometimes 

 the whole body, is rough with large tubercles; in Luxi- 

 lus, PlargyruS) Lythrurus, Gila and Minnilus the 

 prickles are quite small and crowded on the upper surface 

 of the head and neck. 



In some genera, the males in spring are adorned with 

 bright tints of red, which give these little fishes a 

 temporary brilliancy scarcely surpassed even by Trouts 

 or Darters. In JLuxilus, Lythrurus, C ampostoma, and 

 Semotilus^ the red appears chiefly as pigment in the 

 membranes of some or all of the fins, the sides of the 

 body being usually more or less flushed; in Rhinichthys 

 and Gila, the black of a portion of the lateral band 

 usually changes to red; in Chrosomus, and probably 

 Phoxinus, the pigment lies mostly in the skin of the 

 belly, and in Minnilus it is chiefly about the head and 

 the bases of the fins. In Pimephales and Hyborhynchus^ 

 black pigment is deposited in the skin of the head, and 

 in the species of the sub-genus Plargyrus, satin-white 

 pigment occurs in the fins. So far as is known to me, 

 the species of Hybopsis, Hemitremia, Hybognathus, 

 Photogenis, Phenacobius^ Exoglossum, Notemigonus, 

 Ericymba. and the sub -genus Erinemus of Cera- 



