ARIUS, 127 
eye 6. Fontanel produced into a feeble groove which nearly reaches the parieto-occipital ; occipital 
process keeled, subtriangular, about as broad as long, with sides slightly concave and apex more or less 
emarginate ; dorsal shield small, subcrescentic. Width of mouth 4 the width of head; premaxillary 
band of teeth 33 to 4 times as long as broad; teeth on the palate obtusely conical, in 2 rather small 
well-separated subovate patches; maxillary barbel extending to basal part of pectoral. 11 gill-rakers 
on the lower part of the anterior arch. Dorsal 17; spine 2 the length of head ; adipose fin shorter than 
the dorsal. Anal 19-21. Pectoral spine 2 the length of head, with the inner edge very strongly 
serrated. Inner surface of the paired fins blackish. 
Hab. Muxico, Rio Papaloapam®; Guaremana, Rio Motagua! (Salvin). 
Here described from the types of the species, three specimens measuring from 180 
to 200 mm. in total length. 
This is the only member of the genus known from the Atlantic slope of Mexico and 
Central America. 
2. Arius liropus. 
Tachysurus liropus (Bristol), Jord. & Everm. Bull. U.S. Nat. Mus, xlvii. 1900, p. 2784'. 
Hab. Mexico, San Juan Lagoon in Sonora}. 
8. Arius fuerthii, (Tab. XVIII. fig. 2 and Tab. XIX. fig. 8.) 
Arius firthii, Steind. Sitzungsb. Ak. Wien, Ixxii. 1876, p. 579°. 
Tuchysurus furthii, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1900, p. 2787°; Gilb. & Starks, 
Mem. Calif. Ac. Sci. iv. 1904, p. 32°. . 
Tachysurus steindachneri, Gilb. & Starks, t. c. p. 29, t. 5. fig. 9*. 
Depth of body 5 in the length, length of head 32 to 4. Breadth of head 13 in its length, diameter of eye 6 
to 74. Fontanel produced into a groove which does not reach the parieto-occipital; occipital process 
with or without a weak keel, usually broader than long, with straight or concave sides and truncate or 
emarginate apex; dorsal shield small, subcrescentic. Width of mouth 3 the width of head ; premaxillary 
- band of teeth 4 times as long as broad; teeth on the palate obtusely conical, in 2 rather large subovate 
patches which are not very widely separated anteriorly ; maxillary barbel extending to the basal part or 
middle of pectoral. 10 or 11 gill-rakers on the lower part of the anterior arch, Dorsal I 7; spine 
2 to 2 the length of head; adipose fin shorter than the dorsal. Anal 20-24. Pectoral spine # to ? the 
length of head, with the inner edge moderately serrated. 
Hab. Panama 1234 (Boucard, Jordan). 
Here described from five specimens, 190 to 260 mm. in total length. 
4, Arius evermanni. 
Tachysurus evermanni, Gilb. & Starks, Mem. Calif. Ac. Sci. iv. 1904, p. 32, t. 5. fig, 10°. 
Hab. Panama}. | 
Very closely allied to A. fuerthii, but apparently distinguished by the shorter and 
broader occipital process. 
The species is based on a single specimen of 250 mm. 
