140 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
5. Conorhynchos nelsoni, new species. Bay re. 
Type, No. 50001, U.S.N.M., a male, 16 inches long, collected May 8, 1900, by E. W. Nelson and 
E. A. Goldman, in the Rio Usumacinta, Montecristo, Yucatan. Cotype, No. 2382, U. S. F. C. reserve 
series, a male 13.5 inches long, collected at same time and place. 
Head 3.2; depth 5; eye 8; snout 2.1; interorbital 3; D. i, 6; A. 17; gillrakers 10 + 4, short and 
weak, longest scarcely greater than diameter of pupil; gill-arches very convex. Body nearly terete, 
gradually tapering and becoming somewhat compressed posteriorly; width above pectorals not quite 
equal to depth; head conic, about as wide as deep at any point, a granular saddle over occipital region 
extending anteriorly to posterior portion of eye; a small granular saddle at base of dorsal in front, 
posterior edge concave; fontanelle long and narrow, beginning air eye’s diameter in front of eye and 
extending an equal distance behind eye, a narrow transverse bridge equal to diameter of pupil 
just back of posterior border of eye; snout very long, pointed; mouth small, nearly circular, upper jaw 
the longer; barbels all very short; maxillary barbel not nearly reaching eye, its length about 2 in 
snout; other barbels shorter; no teeth on vomer and palatines; teeth on upper jaw confluent in one 
broad patch, concave posteriorly; teeth of lower jaw very weak; buccal cavity very large; roof of 
mouth dome-shaped; eye high, its lower edge on a line with upper part of gill-opening, its distance 
from end of snout equal to distance from center of pupil to gill-opening; origin of dorsal midway 
Fig. 1 . — Conorhynchos nelsoni, new species. The smaller figure is nearly natural size, the other one-third natural size. 
between tip of snout and posterior base of anal; dorsal spine of moderate strength, 2.16 in head, 
slightly granulated along its lower front for half its length, upper posterior third roughly serrated ; the 
first, soft dorsal ray about as high as body; distance between dorsal and adipose fins 1.4 in head; adipose 
fin large, its height 2.25 in that of dorsal fin, its base equal to that of soft portion of dorsal; caudal 
deeply forked, the upper lobe the longer, equal to snout and eye; ventral rays shorter than pectoral 
rays; pectoral fin moderate, its longest ray more than half head, its spine stouter than dorsal, 2.5 in 
head, its posterior edge very strongly serrate; anal large, its longest ray 2.75 in head. 
General color in alcohol, light, brown above lateral line, with bluish reflections; silvery below, 
becoming pale on belly; dorsal pale dusky, spine darker in front; adipose fin color of its dorsal region; 
caudal pale with some indications of yellow at its base and sides, inner edge of lobes tipped with 
black; anal pale; ventrals pale, slightly dusky inside; pectoral pale, dusky on inner side. 
When the type specimen was obtained by Mr. Nelson there were found in its mouth 39 well- 
developed eggs. The cotype, also a male, contained one egg in its mouth. 
This habit of certain cat-fishes of carrying their eggs in the mouth is a curious and very interesting 
one, a habit about which more or less has been known for many years. 
The first and most complete account of this habit of cat-fishes carrying their eggs in their mouths 
is that by Dr. Jeffries Wyman, which he communicated to the Boston Society of Natural History at its 
