EIGENMANN: THE FRESHWATER FISHES OF BRITISH GUIANA 271 



longer than the head; origin of dorsal equidistant from tip of snout and origin of 

 adipose; caudal broad, the rays leathery (usually damaged); anal emarginate, the 

 second and third rays extending past the tip of the last; origin of dorsal and ventrals 

 about equidistant from tip of snout, reaching over half-way to anal; pectorals 

 reaching ventrals, or a little shorter. 



Plumbeous; light streaks extending along the middle of the rows of scales; 

 posterior part of dorsal and middle of caudal barred; lower fins hyaline to dusky. 



This species was abundant on the sand-bar near Rockstone and was also taken 

 in the cataract at Tumatumari. The flesh is soft and specimens are very hard 

 to preserve. 



128. Prochilodus maripicru sp. nov. (Plate XXXV, fig. 2.) 



Type, 282 mm. Maripicru Creek. (Carnegie Museum Catalog of Fishes No. 

 2066.) 



Cotypes, two specimens, 220-375 mm. Maripicru Creek, a branch of the 

 Ireng. (C. M. Cat. No. 1067; I. U. Cat. No. 12255.) 



Head 3.75-4; depth 3; D. 12; A. 10; scales 7 or 8-45-6. Eye 1.75-2 in snout, 

 4.5-4.8 in head, 2.5-3 in interorbital. 



Very near to P. rubrotceniatus, P. argenteus, and P. lineatus, but the head 

 narrower, the mouth nearly a fourth narrower in specimens of equal size, the snout 

 more elongate, projecting beyond the lower jaw; origin of dorsal nearer to adipose 

 than to snout. 



Color much as in P. rubrotceniatus, but the dark streaks between the rows of 

 scales being conspicuous rather than the light band along the rows of scales. 



Subfamily Chilodin^e. 

 Tylobronchus 32 gen. nov. 



Fourth gill-arch dilated behind, its surface corrugated. Anal short, emar- 

 ginate; a single series of feeble teeth in each jaw, those of the upper jaw bifid, 

 three series on the pharyngeals; scales large, serrate; lateral line straight, complete. 

 Mouth small, inferior. 



Anterior air-bladder considerably larger than the eye; the posterior long, 

 straight, tapering to the origin of the anal, 2.66 in the length. Alimentary canal 

 much coiled below the anterior air-bladder, nearly twice the length of the entire 

 fish. Vertebrae 15 + 16, without counting those which are coalesced. 



This genus differs from Ccenotropus in having teeth in the lower as well as in 

 the upper jaw. 



32 tiAos, a swelling; pp6yxos, throat. 



