EIGENMANN: the freshwater fishes of BRITISH GUIANA 437 



Head 4.8-7.1, depth 12.4-13.6 in the length to the end of the anal; snout 1.6- 

 2, interorbital 8-14 in the head; eye 7-14 in the snout. 



Body compressed, slender and quite elongate; width of the head 2-2.5, depth 

 of the head in the occipital region 1.2-1.4 in the greatest depth of the body; anus 

 on or a little behind the vertical from the posterior margin of the eye; dorsal and 

 ventral profiles almost straight; snout produced, straight and tubular, its length 

 varying in a direct ratio with that of the body ; mouth small and somewhat under 

 the upper jaw; gape short, 5-8 in the snout; jaws almost equal, but the lower so 

 included by the hood-like upper that the open mouth is under the upper jaw; 

 teeth wanting. 



Caudal peduncle 3.5-4.5 in the total length; pectorals 1.8-2.8 in the head; 

 origin of the anal on or slightly behind the vertical from the origin of the 

 pectorals. 



Ground-color buff; snout and top of the head more or less completely covered 

 with black, especially the distal half of the snout; a number of irregular black 

 blotches down the middle of the back, and a second row of larger black spots, more 

 or less confluent with the dorsal ones, in the region of the lateral line and above; 

 caudal appendage completely encircled by two or three broad black rings; fins 

 hyaline. All of the black markings vary with the size of the fish. The smallest 

 specimen at hand is almost devoid of black markings, only the dorsal ones being 

 represented by a few scattered dots, while the amount of black steadily increases 

 to the largest, which bears all of the spots described. The snout is also subject 

 to variation, growing longer in the larger fish, hence the rather large range of the 

 measurements in which the length of the head or snout figure. 



Subfamily Sternarchin^. 

 Stern ARCHORHYNCHUS Castelnau. 

 Sternarchorhynchus Castelnau, Anim. Am. Sud, Poiss., 1855, 91, 95. 

 Rhamphosternarchus Gunther, Catalogue, VIII, 1870, 4. 

 Type, Sternarchorhynchus nmlleri Castelnau. 



Caudal fin present; teeth in patches in both jaws; snout long, tubular and 

 somewhat decurvcd; eyes without free orbital margin. 



280. Sternarchorhynchus oxyrhynchus (Miiller and Troschel). 

 Sternarchus oxyrhynchus jVIuller and Troschel, in Schomburgk, Reisen, III, 

 1848, 640 (Lower Essequibo); Hora? Ichth., Ill, 1849, 16, pi. 2, figs. 1 and 2 



