330 Fretp Museum or Natura History — Zoétocy, Vor. X. 
anal of female small, its third ray the longest; modified anal of male 
shorter than the head; ventrals small, not reaching anal; caudal deep, its 
posterior margin rounded. 
Color brownish, bases of scales dark; dorsal region dark, the ventral 
region silvery; dorsal with one to several transverse series of small spots 
of black, the fin sometimes black tipped; caudal with small spots of 
black on basal half, or with a couple of clouded transverse bands; the 
fins uniform or punctulate. (Garman.) 
This species was not seen by us. 
66. Mollienisia formosa (Girard). 
Limia formosa Girard, Proc. Ac. Nat. Sci. Phila., 1859, 115 (Palo Alto, 
Mexico). 
Mollienisia formosa Ginther, Cat. Fish. Brit. Mus., VI, 1866, 349; 
Jordan & Evermann, Bull. U. S. Nat. Mus., XLVII, 1896, 699; 
Regan, Proc. Zool. Soc. Lond., 1913, 1012 (Tampico, Mexico; Colon, 
Panama). 
Head 3.3 to 4; depth 2.5 to 3; D. 11 to 14; A. 9 or 10; scales 26 to 28. 
Body rather robust; eye 3 to 3.5 in head; interorbital 1.7 to 2; origin 
of dorsal a little nearer the base of caudal than the end of the snout; 
origin of anal below fourth ray of dorsal; pectoral shorter than the head; 
caudal fin rounded; least depth of caudal peduncle, 1.3 to 1.6 in head; 
modified anal of male 1.3 in head. 
Color olivaceous; scales with brown spots; dorsal fin with transverse 
series of blackish spots, other fins plain. | 
This species is recorded from Colon by Regan. It does not occur in 
our collections. 
Habitat: Atlantic slope of Mexico and Central America. 
42. Genus Rivulus Poey. 
Rivulus Poey, Memorias, II, 1858, 307 & 383 (type Rivulus cylindraceus 
Poey). 
Cynodonichthys Meek, Field Col. Mus. Pub., Zodl Ser., V, 1904, ror 
(type Cynodonichthys tenuis Meek). 
Slender fishes with subterete body; mouth small, the branches of the 
lower jaw firmly united; teeth conical, in bands, the outer ones enlarged 
and curved; one or two teeth on each side usually enlarged and canine- 
like; margin of eyes not free; pectorals obtuse, low; caudal rounded or 
subtruncate; dorsal small, over posterior part of the much longer anal; 
oviparous; air bladder large; alimentary canal short, about 34 to 34 
length yf body. 
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