L. Agassiz on the Ichthyological Fauna of Western America. 99 
of smaller pores, but larger ones follow the margin of the pre- 
operculum, aud the lower jaw as well as the suborbitals and mas- 
toid bones. 
Unfortunately the two specimens collected in Columbia River 
are deprived of their intestines, and in one of them only, were 
the pharyngeal boues, withtheir teeth, preserved ; but these af- 
ford further evidence of the correctness of my view in consider- 
ing these fishes asa type of a distinct gents peculiar as far as 
is now known to the northwest coast of America. . There is but 
a single row of teeth and only five teeth in that one row on the 
left aud four on the rizht side. The isolated teeth stand ona 
eylindrieal peduncle swelling into an obligne club-shaped crown, 
which is elongated externally into a sharp hook, but the inner 
surface is cut obliquely like the incisors of Rodents, and resen 
a flat grinding surface resembling closely the dentition of Chon- 
drostoma and Chondrochilus, differing however in the more club- 
shaped form of the teeth, and the sharp terminal hook, and also 
the smaller number of teeth iu one row. Fig. 9, a, represents 
the right pharyngeal of Acrocheilus alutacens seen from behind, b 
the sume seen from its inner margin, ¢ one tooth in profile from 
its Upper side, ¢ another from its lower side, and e the same from 
the inner side to show the grinding surface. As a further resem- 
blance to the geuns Choudrostoma, L should mention the eir- 
cumstance, that the peritoreum is also blac 
Acrocheilus alutaceus, Agass. aud Pick. 
Caught at Willamet Falls, and in Wallawalla River. Nose 
Prominent and rounded. 
ail rather slender. Candal large. Dorsal mnch larger than 
the anal. The color light brown above, (there being a white and 
Very fine line on the edge of each scale,) blending into yellowish 
brown upon the sides, and passing into pure white upou the ab- 
domen.  Gill-cover golden brown. wsal and caudal of the 
same color as the sides of the body. Pectorals orange, gradually 
paler towards the base, Ventrals as the pectorals, but more uni- 
formly Orange. Anal also orange, but more bright and reddish. 
It occurs in the rapids and falls of the River. Is caught by the 
natives whule fishing in the Falls for Salmon. 
: (To be continued.) 
