MESOZOIC VERTEBRATA. 
27 
Syllaemus latifrons, Cope. 
Report U. S. Geol. Surv. Terrs., ii, p. 181. 
Represented by the entire head and body of a fish as far as the basis 
of the ventral fins, excepting the end of the muzzle. The scales are com¬ 
pletely preserved, while only the bases of the fins remain. 
The body is subcylindric, while the head is broad and flat above. The 
inferior side of the head is contracted; the coracoids forming a keel, and 
the lower borders of the dentary bones being in contact. The angular por¬ 
tion of the dentary is strongly grooved on its inferior surface, and the prox¬ 
imal or anterior parts of the operculum display a radiate sculpture. The 
top of the head is smooth, excepting a slight radiate sculpture of the parie- 
tals. The outline of the parietals is subround, and a little more extended 
than that of the supraoccipital, which is a short longitudinal oval. 
There are twenty-six or twenty-seven longitudinal rows of scales, or 
thirteen on each half; those of the abdomen not differing from those of tlie 
sides. The lateral line runs along the eighth below the dorsal fin, originat¬ 
ing just above the base of the pectoral fin. There are nine rows of scales 
between the occiput and the first dorsal ray. I count the bases of fifteen 
dorsal radii, which are all fissured anteriorly, excepting the first, which is 
rudimental. The anterior rays are stouter than the posterior, and they em¬ 
brace the posterior part of the ray in front of them by the basal fissure. 
The posterior rays are much narrowed, and embrace but little. The pec¬ 
toral rays are numerous. The physiognomy of this fish is rendered pecu¬ 
liar by the depressed form of the snout, with the narrow under jaw. It is 
impossible to be sure whether the muzzle was elongate or not. 
Length of the specimen to the base of the ventral fin... 0.205 
Length of the specimen to the base of the dorsal. . 0.090 
Length of the specimen to the base of the pectoral.. 0.076 
Length of the specimen to the edge of the operculum. 0.071 
Length of the specimen to the edge of the preoperculum. 0.055 
Length of the specimen to the condyle of the mesopterygoid. 0.029 
Length of the specimen to the orbit.. 0.017 
Diameter of the front between the orbits. 0.020 
Diameter of the body at the middle of the dorsal fin... . . 0.045 
Depth of the body at the middle of the dorsal fin. 0.050 
