FISHES FROM THE RIVERS OF MEXICO. 
139 
Measurements of six specimens of Chirostoma diazi. 
Measurements. 
Collected in G uadalajara market. Said 
to come from Laguna de Chapala. 
' Length of body in millimeters 
185 
188 
.188 
186 
183 
183 
Depth of body expressed in hundredths of length 
19 
20£ 
22 
20 
20 
21 
Depth of caudal peduncle 
8* 
8b 
9 
9 
9* 
9 
Length of head 
30* 
30 
31 
31 
31 
31 
Distance from snout to occiput 
22* 
22 
23* 
22 
23L 
22 
'l ip of lower jaw to occiput 
24 
23* 
25 
24 
25 
2*4 
Width of interorbital space 
6* 
0 
7 
6* 
6* 
G* 
Length of snout 
12 
12 
13 
12* 
13 
12* 
Diameter of orbit 
5 h 
6 
5* 
5* 
5* 
5* 
Distance from snout to spinous dorsal fin 
57* 
55 
55& 
57* 
56* 
57* 
I usertion of spinous dorsal to soft dorsal 
14 
14 
14* 
13 
15 
134 
Height of longest dorsal spines 
7 
U 
G* 
7 
7 
7 
Height of longest dorsal rays 
12 
12 
14 
13 
12 
12* 
Distance from snout to anal fin 
63 
64 
06 
06* 
66 
66* 
Height of longest anal rays 
12 
13 
13 
13* 
13 
13 
Distance from anal to caudal fin 
17 
18 
18 
20 
19 
17 
Lengtli of caudal tin 
18* 
20 
22 
23 
20 
22 
Length of pectoral fin 
17 
16 
19 
19 
18* 
18 
Distance from snout to ventral tin 
48* 
47 
50 
50 
50 
50 
Length of ventral tin 
9* 
10A 
10 
10* 
10 
10 
Number of spines in first dorsal ... 
4 
4 
5 
5 
5 
4 
Number of rays in second dorsal 
12 
11 
12 
11 
11 
12 
Number of rays in anal 
21 
21 
21 
20 
21 
22 
Number of rays in pectoral 
15 
15 
15 
15 
15 
15 
Number of scales in lateral series 
01 
70 
63 
69 
60 
63 
Number of scales in transverse series 
21 
20 
20 
20 
20 
20 
N amber of scales between dorsals 
21 
27 
21 
22 
26 
23 
34. Chirostoma crystallinum Jordan & Snyder, new species. Fig. 16. 
Type No. 6158, L. S. Jr. Univ. Mus. Locality, Laguna de Chapala, near Ocotlan, Jalisco, Mexico. 
Collected by J. O. Snyder, December 26, 1898. 
Head 3.25 in length; depth 4.75; depth of caudal peduncle 3.50 in head; eye 5.75; snout 2.60; 
interorbital space 4.50; height of spinous dorsal 4.20; soft dorsal 2.50; anal 2.25; length of pectoral 
1.80; ventral 2.75; caudal 1.75. D. v-13. A. 24. P. 16. Scales in lateral series 56 ; transverse series 
18; between dorsals 10. 
Body deepest above ventrals ; widest at insertion of pectorals. Head long and pointed, its upper 
contour straight ; snout viewed from above sharply pointed, the lower jaw projecting beyond upper a 
distance equal to a little more than half the diameter of pupil ; eye nearer tip of snout than to posterior 
edge of opercle a distance equal to diameter of pupil; month oblique, the cleft extending downward 
to a level with lower edge of pupil; lips thickened posteriorly, the lower folding over the upper at 
angle of mouth. Teeth minute, in wide patches — not arranged in definite rows — on upper aud lower 
jaws; no teeth on vomer or palatines. Gillrakers 
on first arch 27, slender, the length of longest equal 
to diameter of pupil. Vertebra-. 44. 
An indefinite lateral line extending along the 
body about 9 scales below first dorsal; the pores 
absent on many of tbe scales. Scales crenate, larg- 
est along color-band, growing smaller above and 
below, much smaller and closely crowded on body 
anterior to pectoral fin from isthmus to occiput; a 
few small scales at upper end of opercle, along bases of fins, and on interradial membranes of caudal 
tor half its length : scales between dorsals large and not crowded together ; lower jaw and upper part 
of snout naked. First 3 spines of dorsal about the same length, reaching, when depressed, to within 
one third of their length of insertion of soft dorsal; first dorsal ray longest, others gradually shorter; 
anal inserted on a perpendicular passing through a point halfway between origins of dorsals, base 
much longer than that of dorsal; first dorsal ray highest, others gradually shorter to middle of fin; 
all ot remaining rays of about the same height; caudal deeply forked, tips bluntly pointed, pectorals 
pointed, extending a little past bases of ventrals; tips of ventrals extending to vent. 
Body during life translucent, with a slightly bluish tinge; in alcohol yellowish; dorsal scales 
with dusky edges; top of head dusky; upper part of eye dark; fins, except ventrals and anal, with a 
little dusky color; a silvery color band extending from upper part of pectoral base to caudal; 
narrower on caudal, widening at base of caudal. 
C. crystallinum closely resembles C. ovotlane in general appearance. The much shorter lower 
Fig. 17. — Dorsal view of head of Chirostoma crystallinum. 
