Labyrinthici and Holconoti 379 
four times larger than the young of a Pomotis (of the same 
size) a full year old. In this respect these fishes differ from all 
the other viviparous species known to us. There is another 
feature about them of considerable interest, that while the two 
Fie. 312.—Viviparous Perch (male), Hysterocarpus traski Gibbons. Battle Creek, 
Sacramento River. (Photograph by Cloudsley Rutter.) 
adults differ markedly in coloration, the young have the same 
dress, light yellowish olive with deeper and brighter transverse 
bands, something like the young trout and salmon in their parr 
dress.” 
