GILL] NOTEWORTHY EXTRA-EUROPEAN CYPRINIDS 303 
from the Greek intensive particle gge and the noun xn, cavity. 
The species is pretty wide spread in the country watered by the 
northern and eastern affluents of the Mississippi and extends north- 
ward into Michigan and southward into West Florida, and where 
Fic. 43.—Ericymba buccata. After Jordan and Evermann. 
it does occur, is tolerably common and “locally very abundant.” 
It rarely attains a length of five inches. 
The interest of this genus is in the fact that it repeats in the family 
of Cyprinids a characteristic which is manifest in isolated genera 
of a number of other families, but notably in the fresh-water Percids 
(as in Acerina or Cernua) and Cichlids (as in the Trematocara of 
Lake Tanganyika). It will be an interesting study for future natural- 
ists to investigate the correlation between this structural feature 
Fic. 44—Horny Head, Hybopsis kentuckiensis. After Goode. 
and habits and to ascertain whether the analogous structures are 
adaptive to identical or different conditions. Cope evidently assigned 
too much relative importance to the character by giving to it 
subfamily rank and isolating the genus from all others. 
