336 Fishes of Upper Georgia. 



I retain the name Photogenis provisionally for a large 

 group of related fishes which form a most characteristic feature 

 of the "Minnow-fauna" of the southern states. Cyprinella 

 is very closely related to JSfototropis, the form of the scales 

 being the only tangible generic difference, and that probably 

 is of little importance. 



The species, however, have a number of superficial charac- 

 ters in common. The mouth is sub-inferior in all, and the 

 snout and ante-dorsal region is covered with small white 

 tubercles in spring. The dorsal has a large black spot on 

 the membrane between the last rays. This is always present 

 in adults, and is most distinct in males. In all species known 

 to me, the tip of the dorsal, anal, and caudal fins is filled with a 

 shining satin-white pigment in spring and summer, a charac- 

 teristic and most exquisite feature of coloration. The species 

 are most readily known in life by their color-markings, which 

 are more varied than in any other genus of Cyprinidre, 

 although not so gaudy as in several others. It is necessary 

 to take account of these coloration features in the discrimina- 

 tion of species', although immature and alcoholic specimens 

 show them imperfectly. 



The case is similar to that of the genus Dendroeca among 

 birds. It would puzzle any ornithologist to identify our 

 Avarblers with the feathers plucked off — i. e., with the colora- 

 tion lost. 



The species now referred to Photogenis, agree in the/ollow- 

 ing characters : — 



Body more or less compressed, covered with rather large scales, which 

 are closely and smoothly imbricated, the exposed surfaces being higher 

 than long. Head moderate or rather small, with a rather small eye. 

 Mouth not large, usually little oblique, and typically slightly overlapped 

 by the upper Jaw. No barbels. Ventral fins somewhat in advance of dorsal. 

 Anal fin short (except in grandipinnis, pyrrhomelas, and xcenurus ) Pha- 

 ryngeal teeth hooked, without masticatory surface, their edges sharp and 

 always entire. Teeth 1, 4-4, 1 (rarely one-rowed). Snout tuberculate, 

 and fins with white pigment, in spring males. Photogenis is distinguished 

 from Lythrurus by the sharp edged teeth, which have no grinding sur- 



