DR. GUNTHER ON THE FISHES OF CENTRAL AMERICA. 475 
caudal); the length of the head five times. The lower jaw is slightly shorter than the 
upper. Interorbital space flat, its width being less than twice the width of the eye. 
Dorsal fin with the spine very feeble, somewhat higher than long. Pectoral fin rather 
short, as long as the head, without snout; its spine about double the length of the 
humeral spine. Porus axillaris distinct. Ventral rather longer than the pectoral. 
Anal fin with the base longer than that of the dorsal; its rays do not extend nearly to 
the end of the adipose fin if laid backwards. Caudal cleft to the base ; its upper lobe 
less rounded and narrower than the lower one, which is one-seventh of the total length. 
Coloration uniform, dorsal fin with a whitish cross band. 
One specimen, 9 inches long, was obtained by Capt. Dow in the Lake of Managua. 
214. ARIUS ASSIMILIS. 
Ginth. Fish. v. p. 146. 
Doe 2AS19;) sPi Ly t0: 
The height of the body is contained four times and two-thirds in the total length 
(without caudal), the iength of the head thrice and three-fifths; head much broader 
than high, its greatest width being three-fourths of its length. Eyes rather small, 
situated nearer to the end of the snout than to that of the operculum; the length of 
the snout is three-fifths of the width of the interorbital space. The median longitudinal 
fonticulus on the upper side of the head does not extend to the base of the occipital pro- 
cess. ‘Teeth on the vomer but slightly separated in the middle, forming free 
a pair of oblong transverse patches, which are confluent with those on / apes Lae 
the palatine bones; the latter are short, club-shaped. ‘The band of Ce a 
intermaxillary teeth is five times as broad as long. All the teeth villi- ee \ 
form. ‘The maxillary barbels extend nearly to the end of the head; the 
length of the outer ones of the mandible is one-half or two-thirds of that of the head. 
Crown of the head granular, the granulations being arranged in radiating streaks. 
Occipital process broader than long, triangular, with its hinder end concave. The 
basal bone of the dorsal spine of moderate size, crescent-shaped. Dorsal spine of 
moderate strength, more than half as long as the head, granulated in front and slightly 
“serrated behind; the first soft ray is longer than the spine and as high as the body. 
Adipose fin shorter than the dorsal. Caudal deeply forked, with the upper lobe 
longest, its length being contained five times and a half in the total. Pectoral spine 
serrated along its inner edge and on the extremity of the outer edge. Ventral fin 
shorter than pectoral. Sides of the body silvery; vertical fins greyish; basal half of 
the inner side of the paired fins black. 
One example, 15 inches long, was obtained by Messrs. Godman and Salvin in the 
Lake of Yzabal. 
Hexanematichthys hymenorrhinos, Bleek. Vers]. & Mededeel. Akad. Wetensch. Amsterd. 
1862, xiv. p. 577, appears to be closely allied to the above species; and we should not 
Sy 
