1 
9 
oO 
4 
OSTARIOPHYSI. 
Depth of body 6 in the length, length of head 5. Breadth of head 12 in its length, length of snout 23, 
diameter of eye 51, interorbital width 4. Lower jaw nearly as long as the upper; width of mouth = the 
width of head. Maxillary barbel extending nearly to the posterior end of pectoral fin. Head covered 
with smooth skin ; occipital process extending 4 of the distance from its base to the origin of dorsal. 
9 to 11 gill-rakers on the lower part of anterior arch. Dorsal I 6; spine slender, fin rounded. Length 
of adipose fin 22 in the length of the fish. Anal 14, when laid back not nearly reaching the vertical from 
the end of adipose fin. Humeral process extending a little beyond the middle of pectoral spine, which 
has the inner edge serrated and measures 2 the length of the fin or 2 the length of head. Ventrals 
inserted behind the last ray of dorsal, extending 2 of the distance from their base to the origin of anal. 
Caudal deeply notched, the lower lobe rounded. Least depth of caudal peduncle 23 in the length of head 
and 23 in the distance from anal to base of caudal. Brownish. 
Hab. Nicaragua, Lake Managua! (Dow). 
Here described from the type, a specimen measuring 210 mm. in total length. 
11. Rhamdia heteracantha, sp. n. 
Depth of body 52 in the length, length of head 41. Breadth of head 14 in its length, length of snout 23, 
diameter of eye 52, interorbital width 3. Lower jaw scarcely shorter than the upper ; width of mouth 3 
the width of head. Maxillary barbel extending to origin of adipose fin. Head covered with smooth 
skin ; occipital process triangular, extending about 2 of the distance from its base to the origin of dorsal. 
7 gill-rakers on the lower part of the anterior arch. Dorsal 16; spine slender, fin rounded. Length of 
adipose fin nearly 3 in the length of the fish. Anal 10. Humeral process extending nearly to middle of 
pectoral spine, which has the inner edge finely serrated and a series of antrorse denticulations on the 
outer edge and measures 3 the length of the fin and 2 to 4 the length of head. Ventrals inserted behind 
the last ray of dorsal, extending 2 of the distance from their base to the origin of anal. Caudal 
moderately notched. Least depth of caudal peduncle 21 in the length of head and 12 in the distance 
from anal to base of caudal. Brownish. 
Hab. Costa Rica, Juan Viiias (Underwood). 
A single specimen, measuring 105 mm. in total length. 
12. Rhamdia hypselura, (Tab. XXI. fig. 3.) 
Pimelodus hypselurus, Giinth. Cat. Fish. v. p. 126 (1864) '. 
Rhamdia hypselurus, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 152°. 
Depth of body about 53 in the length, length of head 43. Breadth of head 1; in its length, length of snout 
23, diameter of eye 53, interorbital width 3. Lower jaw shorter than the upper; width of mouth 
slightly more than 2 the width of head. Maxillary barbel extending to middle of dorsal fin. Head 
covered with smooth skin; occipital process extending # of the distance from its base to the origin of 
dorsal. 9 gill-rakers on the lower part of the anterior arch. Dorsal I 6; spine slender, fin rounded. 
Length of adipose fin 33 in the length of the fish, Anal 13, Humeral process extending to middle of 
pectoral spine, which is 3 the length of the fin and 3 the length of head. Ventrals inserted behind the 
last dorsal ray, extending 2 of the distance from their base to the origin of anal. Caudal moderately 
notched. Least depth of caudal peduncle 12 in the length of head and 13 in the distance from anal to 
base of caudal. Dark greyish. 
Hab. Mexico! (Parudazkt). 
Here described from the type, a specimen measuring 115 mm. in total length. 
