94 L. Agassiz on the Ichthyological Fauna of Western America. 
their Catostomns congestus and insignis I must refer to 
car rema.ks under the head of Moxostoma and Prychostomus. 
Catostormus Bostonensis, Les., Cat. pallidus, DeKay, and flore- 
alis, pair are so closely allied that 1 am unable to distinguish 
them; I have however seen only one specimen of the latter. As 
to Cat, Peels Val., it has not been seen since Tilesius described 
it under the name of Cyprinus rostratus, and its true affinities 
remain still doubtful. 
Catostomus occidentalis, Agass. 
This species resembles very closely C. communis, in general 
ontline and appearance, but differs from it in the following re- 
spects. ‘The head is less square ; the profile steeper, but the snont 
is more pointed. The sides of the head are nearly triangular 
instead of trapezcidal and converge more rapidly forwards. ‘The 
longitudinal rows of tubes upou the top of the head are more 
waved. The mouth is smaller; the hind margin of the lower 
lip is perpendicularly under the anterior nasal opening. The 
lower border of the eye and the posterior angle of the opercle are 
on the same esha line. ‘The centre of the eye is nearer the 
anterior edge of the upper lip than the hind or lower angle of the 
subopercle. "The opercle aud subopercle are larger and longer 
aud together form one-half of the side of the head. The lowest 
angle of the opercle is less acute, and its hind angle smaller ; i its 
waving border is directed more forwards and backwards. 
The pectorals are broader; the dorsal is longer, considerably 
emarginated above, its last rays shorter and its upper angle more 
acute. ‘The ventrals are more pointed 
The scales on the anterior part of the body are smaller. 
TRIBE OF CHONDROSTOMI, 
There lives in Europe a remarkable fish of the family of Cyp- 
rinoids which was first described by Linneeus as Cyprinus Nasus, 
and in which I recognised about twenty years ago the type of a 
distinct genus, Chondrostoma. ‘This fish differs so strikingly 
from the other Cyprinoids that Heckel in his synopsis, considers 
it as the type or a distinet tribe, to which he ascribes the follow- 
ing characters 
‘Os inferum in aciem cartilagineam attenuatum, labiis et plica 
menti deficientibus ; rostrum incrassatum ; preopereulum he gens 
oceiput. Pinna dorsalis snbelongata, analis brevis, utraque i 
osseo nullo. 'Tractus intestinalis longissimus tenuissimus. 
"The cartilaginous lips, with a sharp edge of the lower lip at 
least and the ehideltike teeth, with a narrow flat grinding surface, 
supported upon pharyn eals the outer margin of which has a 
r 7 ‘in seer Ae of mig nigral 
ve 
lateral: a truly characterist this tribe as a 
ra 
