138 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Body long, deeper, and more compressed tlian that of C. humboldtianum ; head large, its dorsal 
contour straight from tip of snout to occiput; viewed from above the head is much compressed, the 
upper jaw sharply pointed and included hy lower ; interorhital space slightly convex ; eye nearer tip of 
snout than to edge of opercle a distance equal to diameter of pupil ; preorbital area a little wider than 
diameter of orbit; mouth oblique, its cleft extending to a horizontal from lower edge of orbit; lips 
thickened posteriorly, the lower forming a fold across the upper at angle of mouth; lower jaw pro- 
jecting, the teeth just passing the edge of the upper; maxillary extending to a vertical from anterior 
edge of orbit, its distal end angular. Teeth large anteriorly, growing gradually smaller posteriorly, 
canine-like, sharp, projecting backward, not arranged in definite rows; none on vomer or palatines. 
Vertebras 44. No lateral line. 
Scales crenate, larger in region of lateral color-band, growing smaller dorsally and ventrally; 
abruptly smaller and closely crowded together in a region anterior to pectoral fin, extending from 
the isthmus to the occiput, also between the dorsal fins and along the bases of the dorsals, anal, and 
I'ig. 15. — Uhiroxtuma diazi Jordan & Snyder, new species. Type. 
caudal; interradial membranes of the latter with scales extending two-thirds its length. Head with 
scales except on jaws, upper part of snout, and on preorbital area. Anterior spines of dorsal longest, 
others a little shorter; first dorsal ray longest, others gradually shorter; anal similar to soft dorsal in 
shape, except that its base is much longer; insertion of anal on a perpendicular passing halfway 
between dorsals; caudal deeply forked, the lobes obtusely pointed; pectorals sharp, extending past 
base of ventrals a distance equal to diameter of orbit; edge of pectorals, when extended, straight. 
Body during life translucent; in alcohol greenish-olive; a silvery lateral band, in which the 
silver is not underlaid with black pigment, extending from axil to base of caudal; dorsal scales 
narrowly edged with dusky; upper part of eye dark. Our specimens are all from the market, the 
gill-arches and viscera having been removed. The Hesh is somewhat shrunken, which probably 
causes the teeth to appear more prominent than in life. 
Cliirostoma diazi may bo easily distinguished from the other known species of the genus by the 
small scales crowded closely together between the dorsal fins. 
Named for Porfirio Diaz, the honored President of the Republic of Mexico, in recognition of his 
interest in the progress of science. 
