eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 299 



upper jaw with eight teeth in a crescent, the middle ones broad, bilobed, or squarely 

 truncate in the adult, the lateral ones rapidly smaller, obscurely trilobed; lower 

 jaw with similar teeth, more distinctly directed forward, much as in Leporinus; 

 gill-membrane joined to the isthmus; postventral area with an obscure median 

 keel; preventral area in the adult with a median and two lateral keels or angles, 

 the preventral surface to the base of the pectoral being covered with three series of 

 scales. 



In the young the teeth of the upper jaw have several points, and the ventral 

 keels are not evident; the gill-membrane may also form a narrow free fold across 

 the isthmus in the young. 



156. Schizodontopsis laticeps sp. nov. (Plate XLI, fig. 4.) 

 Type, 264 mm. Crab Falls. (Carnegie Museum Catalog of Fishes No. 1825.) 

 Cotypes, two specimens, 96-240 mm. Crab Falls. (I. U. Cat. No. 12116.) 

 A fourth small specimen of this species was taken by Mr. Ellis on Gluck Island. 

 Head 4.2; depth 3-3.16 (4 in young); D. 12 or 13; A. 11 or 12; scales 6-42-4 

 or 5; eye 1.25 in snout, 3.3-3.5 in head, 2 in interorbital in the adult. 



Heavy, the width not quite half the depth; profile arched, comparatively steep, 

 with a slight depression over the eyes; belly with a blunt median keel; two similar 

 lateral keels in front of the ventrals; predorsal region rounded; head broad, some- 

 what depressed, its width at the anterior margin of the eye equal to its depth at 

 the same point; interorbital convex; width of mouth greater than the length of 

 the orbit; mouth oblique, the lower jaw projecting. 



The teeth of the upper jaw graduated, the middle ones broad-lobed incisors, ar- 

 ranged in a crescent; teeth of the lower jaw similar to those of the upper. 



Dorsal subtruncate, rounded in the young, its highest ray about 4.5 in the 

 length; its origin a trifle nearer snout than to tip of adipose; caudal broad, leathery 

 in the adult, the upper lobe not greatly longer than the lower, about 4.5 in the 

 length (4 in the young) ; anal truncate, the first rays not reaching tip of last, not 

 reaching caudal; ventrals not reaching half-way to anal (just half-way in the 

 young) ; pectorals more than half-way to middle of ventrals. 



Ashy gray; a broad obscure band from the dorsal, narrowing to the ventrals; 

 a narrower cross-shade above middle of pectorals and in front of anal; adipose, 

 anal and axil dark. Young with a black band from the chin to the eye and middle 

 of caudal. 



Leporinus Spix. 

 Leporinus Spix, Selecta Gen. et Spec. Pise. Bras., 1829, 65 (novemfasciatum) . 

 Abramites Fowler, Proc. Acad. Nat. Sci. Phila., 1906, 331 {hypselonotus) . 



