18 FISHES FROM BRAZIL 



lated and the curve from the dorsal to the snout much more pronounced 

 than in the Guiana species, being more convex at the nape and concave 

 above the eyes. The head is contained from 3^^ to 3^ times in the length. 

 The eye is contained from 3^^ to 3^ times in the head. Five trilobed teeth 

 are at each side of the upper jaw, and 7 at each side of the lower. They 

 are about as distinct, and sharp, and as well developed posteriorly on the 

 mandible as anteriorly, while in P. dcnticulatus they are lower, blunter, and 

 less projecting posteriorly. The mandible is rather slender; its depth in 

 front is less than half of the diameter of the eye, and is contained 3 times 

 in its own length. In the other species the mandible is very heavy, its depth 

 being equal to three-quarters of the eye, or half of its own length. 



There are 33 ventral scutes besides a paired one in front of the vent 

 and another behind it, but there are none at the side of the vent as in 

 P. denticulatiis, where there are four at each side posterior to the median 

 ones. There are 15 or 16 dorsal rays, and 32 or ZZ anal rays. In other 

 species there are 19 dorsal rays and 35 anal rays. The distance from the 

 dorsal to the adipose dorsal is scarcely shorter than the base of the dorsal, 

 while in P. denticulatus it is not over half as long as the dorsal base. The 

 first anal rays are a little produced beyond the others. The length of the 

 pectoral is contained 1^ times in the head; that of the ventral 2 times. 

 The pectoral reaches to above the ventral base, and the ventral to the last 

 unpaired ventral scute. The scales are larger than in the other species, 

 there being 71 tubes in the lateral line, 82 cross series, and about 32 verti- 

 cally from the lateral line to the front of the dorsal. The scales are rather 

 uneven and difficult to count crosswise, but the difference in size when the 

 scales above the lateral line are directly compared is very striking between 

 the two species, being much finer in P. denticulatus. 



The specimen at hand of P. denticulatiis, and those described by Dr. 

 Eigenmann, are uniform in color, without spots or a dark caudal margin. 

 In alcohol this species is slate-blue above, silvery below and on the side, 

 and the fins yellow at the base. Over the back and upper part of the side 

 are scattered dark blue spots as large as the pupil and smaller. A dusky 

 blotch is just below the anterior part of the lateral line. The caudal is 

 edged with black. 



The type is 6 inches in length, and several cotypes are as large and 

 others slightly smaller. 



53. Pygocentrus piraya (Cuvier). 



One small specimen was taken at Para. The side is closely covered 

 with dusky spots and the posterior edges of the vertical fins are dark. 



