DR. GUNTHER ON THE FISHES OF CENTRAL AMERICA. 467 
is inserted behind the vertical from the upper end of the gill-opening. Dorsal spines 
rather feeble, the length of the twelfth being two-sevenths of that of the head. Pectoral 
two-thirds as long as the head. Upper parts blackish, each scale with a black base ; 
lower parts reddish, with a broad blackish band from behind the pectoral to the base 
of the caudal; many scales within or below the band with a black spot in the upper 
or lower angle; each scale on the side of the head with a black spot; chin and throat 
violet. The spinous dorsal black, with yellowish margin; the soft parts of the vertical 
fins with blackish spots. 
This species inhabits the Lake of Amatitlan, where Mr. Salvin obtained numerous 
examples up to 7 inches in length. 
Description,—The profile of the head and nape forms a curve. Head as high as long ; 
snout rather elevated; preorbital wider than the eye, the diameter of which is a little 
more than one-fifth of the length of the head, and about three-fifths of the width of the 
interorbital space. Cleft of the mouth narrow, horizontal, the upper jaw slightly over- 
lapping the lower, and the maxillary not extending backwards as far as the anterior 
margin of the orbit. The six front teeth of the outer series are the longest, deep 
brown. ‘The orbit is considerably below the upper profile of the head, and somewhat 
nearer to the end of the opercle than to that of the snout. Opercles scaly, the scales 
on the cheek in four or five series, and smaller than those on the opercle. Vertical fins 
not scaly at the base; the soft dorsal and anal do not reach far beyond the root of the 
caudal. Free portion of tail a little higher than long. Caudal subtruncated, two- 
ninths of the total length. Pectoral three-fourths as long as the head; ventral with 
the outer ray slightly produced, rather longer than the pectoral, and reaching nearly to 
the vent. 
186. Heros trrecunaris. (Plate LX XVIII. fig. 2.) 
Theraps irregularis, Giinth, Fish. iv. p. 284. 
D. 5 A.@? L. lat. 35. L. transv. 4/14. 
The fold of the lower lip is interrupted in the middle. The height of the body is 
nearly equal to the length of the head, which is two-sevenths of the total (the caudal fin 
not included). Head longer than high, with the snout compressed and prominent; the 
length of the snout is two-fifths of that of the head, and twice or more than twice the 
width of the orbit. The cleft of the mouth is small, extending backwards somewhat 
behind the vertical from the nostril; upper jaw slightly overlapping the lower; teeth 
in a narrow band, those of the outer series largest. Preeorbital wider than the orbit, 
its width being equal to that of the interorbital space, which is rather convex. he eye 
is situated immediately below the upper profile, its centre being a little behind the 
middle of the length of the head. Scales on the cheek small, in six oblique series, 
Seales on the opercles as large as those on the neck; those near the base of the dorsal 
-and on the abdomen very small. Scales finely serrated. The dorsal fin commences 
382 
