14 ON SPECIES OF CYNOPOTAMUS. 
rays in the anal vary from 42 to 46. Huh. Rosario, 
Goyaz, and Sao Paolo. 
Cynopotamus biserialis sp.n. 
D. 11, A. 47, V. 8, P. 13, L.l. 62, L.tr. 4^' 
Both upper and lower jaws without external toothlike 
processes; no canines; teeth conical, in two series on in- 
termaxillaries and on the anterior halves of the mandibles ; 
a single series of maxillary teeth. The two series of teeth 
on the mandibles serve as a ready means of distinguishing 
this species from G. gibbosus, and 0. pauciradiatus, which 
it approaches in shape. The back is elevated, decurved 
toward the occiput, and the depth is one-third of the 
leno;th to the bottom of the caudal notch. The head is a 
little more than one-fourth of the length, excluding the 
caudal. Eye large, two and two-thirds times in length of 
head, wider than interorbital space. The maxillary near- 
ly or quite reaches a vertical through the centre of the 
eye. The fourth or fifth ray of the dorsal fin is in the 
middle of the entire length, without the caudal, and the 
anterior ray of the dorsal is slightly behind that of the anal. 
Flanks silvery, humeral and caudal spots present. Many 
examples were secured by the Thayer Expedition at Lago 
do Maximo, Obydos and Villa Bella. 
