FISHES FROM THE RIVERS OF MEXICO. 
133 
The following table of measurements will aid in distinguishing the species: 
Measurements of eleven specimens of Xipliopliorus montesumw. 
Measurements. 
Locality : 
Rio Yerde, near Rascon, Mexico 
Male. 
Female. 
Length of body in millimeters 
574 
52 
57* 
51 
56 
GO 
60 
53 
55 
51 
Depth of body expressed in hundredths of 
length 
344 
34 
36 
33 
36* 
36 
36 
33 
33 
32 
Depth of caudal peduncle 
224 
22 
21 
20 
20 
20 
19 
18 
17 
18 
Length of head 
23 
24 
23 
23 
23 
24 
23 
24 
23 
23 
Hi 
12 
12 
11 
12 
12 
12 
12 
12 
12 
Length of snout 
7" 
8 
8 
8 
8 
8 
8 
8 
lb 
8 
“Width of mouth 
7 
74 
74 
n 
8 
7 
7 
74 
7 
7| 
Diameter of orbit 
8 
74 
74 
8 
8 
7 
7 
8 
74 
8 
Distance from snout to dorsal tin 
46 
47 
47 
46 
47 
49 
49 
49 
50 
48 
Height of longest dorsal rays 
31 
28 
24 
25 
22 
20 
16 
14 
15 
16 
Distance from snout to anal fin 
55 
58 
58 
55 
57 
59 
61 
61 
64 
63 
Height of longest anal rays 
19 
22 
22 
20 
21 
17 
16 
10 
17 
17 
Distance from anal to caudal fin 
46 
42 
45 
43 
40 
40 
364 
34 
32 
35 
Length of upper caudal rays 
33 
35 
29 
30 
32 
27 
30 
28 
28 
30 
Length of lower caudal rays 
90 
88 
60 
43 
43 
36 
30 
29 
30 
30 
Length' of pectoral fin 
25 
26 
23 
25 
25 
24 
24 
22 
23 
22 
Distance from snout to ventral tin 
49 
50 
50 
48 
49 
52 
48 
48 
49 
49 
23 
19 
19 
m 
10 
15 
15 
16 
16 
Number of rays in dorsal 
13 
11 
12 
12 
12" 
12 
13 
ii 
n 
12 
Number of rays in anal 
7 
7 
7 
7 
7 
7 
7 
7 
7 
7 
Scales in lateral series 
29 
28 
29 
29 
28 
27 
27 
27 
27 
28 
Number of scales in transverse series 
9 
9 
9 
8 
9 
9 
9 
9 
9 
9 
Number of scales on caudal peduncle 
7 
7 
7 
7 
7 
7 
7 
7 
7 
7 
ATHERINIDiE. 
28. Eslopsarum jordani (Woolman). 
Two specimens of Eslopsarum jordani were collected, together with numerous individuals of 
E. arge, from the Rio Verde, Aguas Calientes, Mexico. CMrostoma breve Steindachner is probably 
identical with E. jordani, as supposed by Jordan & Evermann. An examination of a number of species 
of Chirostoma and two of Eslopsarum shows that the number of vertebrae, in addition to the character 
of the scales, furnishes a distinguishing generic feature. 
Vertebra;. 
Eslopsarum jordani 38 
arge 37 
Chirostoma humboldtiannm 44 
chapalse 45 
proraelas 45 
diazi 44 
crystallinum 44 
lermm 44 
oootlane 44 
The species of Chirostoma may be divided into two very marked groups. The one represented by 
the typical species Chirostoma humboldtianum has the flesh firm, opaque, and deep olive-green in life. 
The other ( Let'll ostole ), typified by Chirostoma estor, has the flesh thin, translucent, and very pale. 
There are correlated differences in the firmness of the bones and scales, but thus far we have found no 
tangible character on which to separate Lethostole as a genus from Chirostoma. The known species 
of Lethostole are estor, album, chapalce, grandocule, promelas, diazi, crystallinum, leYmai, and ocotlane. 
29. Eslopsarum arge Jordan & Snyder, new species. Fig. 12. 
Type No. 6154, L. S. Jr. Univ. Mus. Collected by J. O. Snyder January 9, 1899, in Rio Verde, near 
Aguas Calientes, Mexico. 
Head 4.25 in length ; depth 4.33; depth of caudal peduncle 2.75 in head ; eye3.66; suoutS; inter- 
orbital space 3.33; height of spinous dorsal 3.33; soft dorsal 2; anal 2; length of pectorals 1.5; ven- 
trals 2.5; caudal 1.2. D. iv, 8. A. 16. P.13. Scales in lateral series 40; transverse series 11 ; between 
dorsals 5. Body rather thickset, deepest part just anterior to base of ventrals; width of body equal to 
distance from posterior edge of orbit to tip of snout. Eye nearer to tip of snout than to posterior edge 
of opercle a distance equal to diameter of pupil; interorbital space convex; width of preorbital area 
equal to diameter of pupil. Tip of lower jaw projecting beyond that of upper ; mouth large, oblique ; 
lips not much thickened posteriorly, the lower not distinctly folded over the upper at their angle; 
maxillary extending posteriorly to a perpendicular passing through anterior edge of orbit, its distal 
end below the level of eye. Teeth large, sharp, projecting backward, in 2 definite rows on each jaw, 
none on vomer or palatines. Gillrakers on first arch 14, long and slender. 
