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Show 526 MR. G. A. BOULENGER ON FISHES [June 18, A single specimen from Paraguay. This species appears to be nearest allied to P. francisci, Liitk., which is only known to m e from the description. 7. CH^ETOSTOMUS GIGAS, sp. n. 15 upper and 19 lower teeth on each side. Depth of body 4| times in total length, length of head 2J- times. Head a little longer than broad, entirely rough with small spines; snout broadly rounded; diameter of eye 11 times in length of head, 4 | times in interorbital width, 6 times in length of snout; anterior border of orbit with enlarged spinules; no postorbital groove; erectile praeopercular spines very strong, the longest 2\ diameter of orbit; barbel a little longer than diameter of orbit. Throat and belly studded with small rough shields. Dorsal I 10; all the rays rough with spinules, the first measuring § length of head. Pectoral spine as long as head, covered with small spines, the longest of which are hooked and nearly equal diameter of orbit. Ventral I 5, as long as first dorsal ray. Anal I 5. Caudal obliquely truncate, lower ray longest. Shields on body rough with ridges of strong spinules, 25 in a longitudinal series. Brown, densely covered all over with round black spots. Total length 530 millim. A single specimen from Paraguay. This fish, the largest known of the genus, is possibly the adult of C. aculeatus, Perugia, in which, however, the ventral region is entirely naked. 8. HYPOPTOPOMA GUENTHERI, sp. n. Head not narrowed behind the eyes, its width equal to length of posterior border of orbit, its length 2 | to 3 times in total; diameter of orbit 5 to 5 | times in length of head, 2\ to 2 | times in length of snout, 3 to 3| times in interorbital width ; barbel very small; head-shields as in H. thoracatum. Dorsal I 6, first ray as long as head to upper angle of gill-cleft. Pectoral as long as first dorsal ray, extending as far as ventrals, not reaching anal. Caudal deeply notched, middle rays half as long as outer. Two pairs of large, transverse pectoral shields, preceded by a transverse series of four small shields, the outer of which are in contact with the suborbital shields; three or four large ventral shields on each side, the anterior of which are usually separated by an azygos shield. Shields on body spinulose but not keeled, 20 to 22 on each side; 3 shields between the occipital and the dorsal, 12 between the dorsal and the caudal. Olive ; dorsal and caudal fins with black spots, which may form two curved bands on the lower lobe of the caudal. Total length 65 millim. Numerous specimens from Descalvados, Matto Grosso. The fish described and figured by Steindachner as H. thoracatum, Gthr., belongs to a distinct species, for which I propose the name H. steindachneri. His H. bilobatum is distinct from Cope's, which |
