FISHES FROM THE RIVERS OF MEXICO. 
137 
along body about eight scales below the first dorsal, pores absent on some of the scales. Scales 
crenate, largest along lateral color-band; a postoccifiital patch of rninnte, closely crowded scales 
extending backward nearly to a line connecting bases of pectorals ; a narrow band of similar scales 
just posterior to gill-openings and on base of caudal; the latter extending on interradial membranes 
half their length ; scales between dorsals not abruptly smaller than those near by, nor crowded 
closely together; head with scales except on snout, preorbital region, and on lower jaw. 
First 3 spines of dorsal nearly equal in length, the fourth a little shorter ; first dorsal ray longest, 
the others gradually shorter; anal inserted on a perpendicular passing midway between dorsals, first 
ray longest, others successively shorter, edge of fin slightly concave; pectoral pointed, extending 
beyond base of ventrals a distance equal to diameter of pupil ; ventrals not quite reaching vent. 
Color in alcohol yellowish-olive; a distinct silvery lateral band, the light color of which is under- 
laid with dark pigment, extending from upper part of base of pectoral to caudal, wider and brighter 
in color between dorsal and anal, growing narrower on caudal peduncle, widening at its end; scales 
of upper part of body with dusky coloring on edges; dorsals, pectoral, and caudal with dark color; 
eye dusky above, a dark band on interorbital space; snout and jaws black. 
Chirostoma promelas is distinguishable from other known species of the genus by the projecting 
upper jaw and the black-colored snout. One specimen other than the type was obtained. In it the 
projection of the upper jaw is more pronounced than in the type. The gillrakers and abdominal 
viscera had been removed from both before they were purchased. 
Measurements of two specimens of Chirostoma promelas. 
Measurements. 
Collected in Guada- 
lajara market ; said 
to have come from 
L. de Chapala. 
155 
176 
22 
21 
9 
9 
30 
29 
23J 
22* 
23 
2 H 
64 
64 
121 
12 
5 
5 
59 
56 
12 
10J 
8i 
6i 
13i 
11 
65 
63 
15 
13 
18 
18 
20 
18 
18 
17 
50 
474 
12 
10 
4 
4 
11 
ii 
19 
20 
15 
15 
53 
56 
16 
16 
9 
8 
Length of body in millimeters 
Depth of body expressed in hundredths of length 
Depth of caudal peduncle 
Length of head 
Distance from snout to occiput 
Tip of lower jaw to occiput 
Width of interorbital space 
Length of snout 
Diameter of orbit 
Distance from snout to spinous dorsal 
Insertion of spinous dorsal to soft dorsal 
Height of longest dorsal spines 
Height of longest dorsal rays 
Distance from snout to anal fin 
Height of longest anal rays 
Distance from anal to caudal fin 
Length of caudal fin 
Length of pectoral fin 
Distance from snout to ventral fin 
Length of ventral tin.. 
Number of spines in first dorsal fin 
Number of rays in second dorsal fin 
Number of rays in anal fin 
Number of rays in pectoral fin 
Number of scales in lateral line 
Number of scales in transverse series 
Number of scales between dorsals 
33. Chirostoma diazi * Jordan & Snyder, new species. Fig. 15. 
Type No. 6157, L. S. Jr. Univ. Mus. Obtained in market of Guadalajara, Jalisco, Mexico, by J. O. 
Snyder, December 23, 1898; said to have come from Laguna de Chapala. 
Head 3.33 in length ; depth 5; depth of caudal peduncle 3.25 in head; eye 5.33; snout 2.5; inter- 
orbital space 4.5; height of spinous dorsal 4.4; soft dorsal 2.5; anal 2.4; length of pectoral 1.6; ven- 
tral 3; caudal 1.4. D. V-ll. A. 20. P.15. Scales in lateral series 75 ; transverse series 22 ; between 
dorsals 22. 
* Since these pages were put in type we have received a paper entitled “Description of two 
Atherinoid fishes from Mexico,” by Dr. G. A. Boulenger, in the Ann. Mag. Nat, Hist., series 7, vol. v, 
Jan., 1900, pp. 54-55. In this paper two species of Chirostoma are described from specimens collected 
in Lake Chapala by Mr. A. C. Buller. One of these (C. lucius) is perhaps our C. lermce, and the other 
(0. sphyrcena) is our C. diazi. These names of Boulenger have priority over ours, but it is, unfortunately, 
too late to suppress the latter. — D. S. J. 
