GILL] NOTEWORTHY EXTRA-EUROPEAN CYPRINIDS 311 
(up to about eight inches), and which range from New York to 
Mexico; in other words they occur in the streams tributary, directly 
as well as indirectly, to the Mississippi basin, and in those discharg- 
ing west of it in the Gulf of Mexico, but not in those of the Atlantic 
seaboard. The best known species is the Campostoma anomalum 
which ranges from central New York to Tennessee, Texas and 
Wyoming, and was found by Jordan and Evermann to be “ every- 
where abundant in deep or still places in small streams, running 
up small brooks to spawn in spring.” It brings stones together into 
a nest and is known popularly as the stone-roller. 
Fic. 59.—Cut-lips Minnow, Exoglossum mavillingua. After Fowler. 
The Exoglossines, although in general appearance like the ordi- 
nary minnows, manifest a certain peculiarity in physiognomy which 
is soon found to result from the singularly shaped mouth, and espe- 
cially the structure of the lower jaw. The peculiarity of structure 
was first recognized by Cope (1866) who correctly described the 
faremost or principal elements of the lower jaw, “ dentary bones, 
straight and flat, united together throughout their length”; thus 
modified, they simulate a tongue, and to this the name Exoglossum 
(ew, outside, and yAdaoa, tongue) alludes. The tongue-like struc- 
ture, however, has nothing to do with the true tongue unless it be to 
entail a recession of it backwards. As Cope has stated, “ the incom- 
pletely defined body which in this family represents the tongue is 
situated in the back part of the oral cavity, since the glossohyal 
bone is excluded from its usual place, and is short; its approximation 
to the interopercle and ceratohyal, with the basihyal and strongly 
elongate urohyal, defend the lower surface of the head effectually.” 
The linguiform extension of the lower jaw is utilized for the pur- 
