410 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [68] 
This species is one of the most common food-fishes of our southern 
coast, being an excellent pan-fish. Notwithstanding the numerous 
-nominal species which authors have recognized, there is no evidence 
whatever of the existence of more than one species of Leiostomus on 
our coasts. 
The name zanthurus is an unfortunate one, as in this species the 
caudal fin is never yellow. This name came about through confusion 
with Bairdiella chrysura, in which species the caudal fin is bright yel- 
low. 
Genus X V.—PACHYURUS. é 
Pachyurus Agassiz, Spix Pisces Brasiliens., 1829, 123 (squamipennis). 
Lepipterus Cuvier & Valenciennes, Histoire Naturelle des Poissons, v, 1; 1830 
(francisci). F 
TYPE: Pachyurus squamipennis Agassiz. 
This genus is composed of fresh-water Scienoids inhabiting the rivers 
of Brazil. It is well separated from Sciwna (Ophioscion) by the weak 
dentition. Two groups or subgenera are readily distinguished by the 
form of the mouth, the group called Lepipterus agreeing in this respect 
very closely with the species called Pachypops, from which Lepipterus tan 
only be separated by the absence of the small barbels at the chin, which 
are usually present in the species of Pachypops. As these barbels are 
quite small, and in individuals even occasionally absent, Dr. Steindach- 
ner has proposed to unite Pachypops with Lepipterus as a subgenus under 
Pachyurus. There is no doubt that Pachypops, Lepipterus, and Pachy- 
urus together constitute a single natural group. The characters drawn 
from the form of the mouth and of the preorbital are subject to inter- 
gradation. Unless the presence of the barbel can here, as elsewhere, be 
used as a mark of generic distinction, all the species must be placed in. 
Pachyurus. It seems to us, however, that convenience is but served by 
placing all the species in which barbels are habitually developed in one 
genus (Pachypops), and those which never have them in another (Pachy- 
uUrus). » 
ANALYSIS OF SPECIES OF PACHYURUS, 
«. Mouth terminal, oblique, small, but larger than in other species; the maxillary 
reaching front of pupil, its length about 2} in head; jaws subequal; caudal 
fin densely covered with scales, so that it is thick to the touch; preorbital 
scarcely turgid (Pachyurus). 
b. Body compressed; the back elevated, the nape depoaeanly compressed; head low 
and narrow ; profile depressed above the eyes, so that the sharp, projecting 
snout inaves a considerable concavity in the line of the profile; teeth in 
broad bands, all equally minute in both jaws; preorbital broad, broader 
than eye; skull not specially cavernous; pores and slits on snout obsolete ; 
preopercle sharply but rather finely serrate on the bony border; eye large, 
5¢in head; snout 3%; interorbital width 5}; gill-rakers almost obsolete, 
2-+ 4in number, not higher than wide; pseudobranchiw small; caudal fin 
rhombic, much thickened; soft dorsal scaly, but not thickened; longest 
