470 DE. GUNTliEE ON THE FISHES OF CENTEAL AMEEICA. 



also closely allied to Etroplus, which f?cnus, however, has but a rudiinentaiy lateral line, 

 wliilst in Aeefroplus it is as much developed as in Heros. 



190. Neetroplus nematopus. (Plate LXXIV. tig. 4.) 

 D. jj. A. % L. lat. 34. L. transv. 51/12. 



The fold of the lower jaw interrupted in the middle ; five series of scales on tlie 

 cheek. Incisoi'S g-. The outer ventral ray produced into a filament as long as the fin. 



One specimen, 4^ inches long, was discovered by Capt. Dow in Lake Managua. 



Bescrvption. — The height of the body is contained twice and three-fifths in the total 

 length (without caudal), the length of the head thrice and two-fifths. Head as high as 

 long, with an adipose prominence over the eye, which renders the profile of the fore- 

 liead somewhat abrupt; snout rather compressed and prominent, the length of the 

 snout is two-fifths of that of the head, and more than the width of the orbit, which is 

 nearly one-third of the length of the head. Cleft of the mouth small, extending back- 

 wards somewhat behind the vertical from the nostril ; jaws equal in front ; teeth in a 

 band, those of the outer series being genuine incisors, which appear to be replaced by 

 smaller ones, standing behind in a band. Praeorbital wider than the eye, equal in width 

 to the interorbital space, which is convex. The eye is situated at some distance from 

 the upper profile, nearer to the end of the opercle than to that of the snout. Scales on 

 the cheek small, in about five oblique series. Posterior limb of proeoperculum about 

 twice as long as the inferior, and descending obliquely forwards. Scales on the 

 opercles as large as those on the neck ; those near the base- of the dorsal and on the 

 abdomen very small. The dorsal fin commences above the vertical from the hinder 

 margin of the operculum. Dorsal and anal scaly at the base. Spines rather strong, 

 the sixteenth dorsal spine being nearly one-half of the length of the head. The soft 

 portions of both fins are produced, and reach beyond the middle of the caudal. Caudal 

 truncated. Pectoral shorter than the head. Outer ray of ventral produced into a 

 filament as long as the fin. Brownish-olive, with irregular darker clouds. 



MlCRODESMrs. 

 (Uinth. Proc. Zool. Soc. 1864, p. 2G. 



Body much elongate, eel-like, covered with rudimentary scales. Head rather short. 

 with snout obtuse, cleft of the mouth narrow, and lower jaw prominent. Eyes minute. 

 Teeth in both jaws minute ; palate toothless. The gill-opening is reduced to a small 

 slit in front of the pectoral fin. Vertical fins united by a membrane ; but the caudal 

 can be easily distinguished from the two other fins. Dorsal fin very long, composed of 

 fiexible, undivided rays, like the anal. Pectorals short ; ventrals thoracic, each reduced 

 to a single ray. Vent in the middle of the total lengtli. 



1 am not able at present to add anything to the knowledge of tliis fish \^ hich would 

 elucidate its natural affinities and indicate its systematic position. 



