PISHES—CYPRINIDAE-CATOSTOMI. 
217 
of the side of the head. The anterior margin of the dorsal is nearer the tip of the central rays 
of the caudal than the extremity of the snout. The base of the anal enters but eleven times in 
the total length. The insertion of the anal is comparatively more anterior than in M. conoce- 
phalus, and that of the ventrals also. We count the rays as follows : 
D 2, 8 + 1 ; A 2, 8 + 1; C 6, 1, 9, 8, 1, 6 ; Y 1, 9 ; P 18. 
The dorsal scales appear to be sub-circular, deeper than long; whilst those of the lateral 
line and of the abdominal region are longer than deep and somewhat irregular in their outline. 
The largest specimen, from which the accompanying figure was made, measures eighteen 
inches and & half in total length. 
The one received from Dr. Ayres is smaller, measuring but sixteen inches. Both were 
purchased in the market of San Francisco, and are reported as having been caught in the San 
Joaquin river. 
References to the figures .—Plate XLVII, fig. 1, represents Mylo'pharodon robustus, reduced in 
size. Fig. 2 is a scale from the dorsal region. Fig. 3, a scale from the lateral line. Fig. 4, 
a scale from the abdominal region. 
List of specimens. 
Catal. 
No. 
Corres. No. 
of teeth. 
NO. Of; 
spec. 
Age. 
Locality. 
When col-! 
lected. 
Whence obtained. 
Orig’l 
No. 
Nature of 
specimen. 
Collected by— 
244 
2796 
i 
Adult. 
San Francis¬ 
co, Cal_ 
1855 
Lt. R. S. Williamson- 
Alcoholic. 
Dr. JohnS. Newberry. 
934 
i 
..do.. 
_do. 
1856 
Dr. W. 0. Ayres_ 
1 
_do_ 
Dr. W. 0. Ayres __ 
TKIBE OF CATOSTOMI 
The distinguishing characters of the suckers or Catostomi as a peculiar group consist, in 
the first place, in the structure and position of the mouth, which is surrounded with large and 
fleshy lips, situated under the protruding snout, and in the absence of barbels. The pharyngeal 
bones are sickle-shaped, varying in the curvature of the dental portion and also in the inferior 
branch. The teeth are numerous, disposed upon one single series ; the inferior ones being 
longest, the others diminishing in size upwards. To use the expression of Heckel, the teeth 
are pectiniform ( Dentes pectiniformis), that is, arranged like a comb. The anterior margin of 
the dorsal fin is situated in advance of the insertion of the ventrals. 
Modifications of these characters, associated with others, will furnish the means of distin¬ 
guishing the genera. 
Syn. — Catostomi, Agass. in Amer. Journ. of Sc., 2d series, XIX, 1855, 73.— Grd. in Proc. Acad. Nat. Sc. Philad., VIII, 
1856, 170. 
The scarcity of materials at our command will compel us to give a very brief diagnosis of 
the generic characters to be assigned to Carpiodes. 
28 a 
