EDWIN CHAPIN STARKS 21 



length is the same (about 3 times). The anal has from 45 to 47 rays, and 

 its base is contained from 3^ to 4 times in the length. The caudal is 

 rounded and the middle rays are not produced with the lateral line. The 

 ventrals are a little more than half as long as the head. The anal and 

 caudal are very closely covered with scales. The scales on the body are 

 slightly ctenoid. A large black spot is present on the shoulder girdle 

 above, a small one on the base of the lower pectoral ray, and one on the 

 adipose dorsal. 



63. Hydrocynus cuvieri (Agassiz). 



This species is not uncommon in the market at Para, where a number 

 of specimens were collected. As our steamer entered the Rio Para, numbers 

 of what appeared to be this form could be seen darting swiftly over the 

 surface of the stream, with the greater part of their bodies out of the water. 



64. Hoplias malabaricus Bloch. 



This species was taken at Cedro Dam, near the town of Quixada, at 

 Ceara Mirim, at Lake Extremoz and at Lake Papary. 



65. Hoplerythrinus unitseniatus (Spix). 



One specimen was found in the market at Para. I may here call atten- 

 tion to an evident mistake in Dr. Eigenmann's key to the family Characidae 

 (Freshwater Fishes of British Guiana, p. 258). For the above genus and 

 for Erythrinus the walls of the anterior portion of the air-bladder are said 

 to be cellular. In our representatives of this genera it is the second chamber 

 of the air-bladder, the part behind the pnetimatic duct, that is cellular. 

 The walls of the anterior chamber and the posterior part of the posterior 

 chamber are simple in structure. 



Family GYMNOTID^. 



66. Sternarchus macrolepis Steindachner. 



A few specimens were taken at Para. The teeth in the upper jaw are 

 extremely easily lost, and ih about half of the specimens at hand they are 

 not to be detected. There is considerable variation in the length and 

 slenderness of the tail and in the position of the vent. 



67. Sternarchus albifrons (Linnaeus). 



A single specimen was found in the market at Para. It has 15 scales 

 between the lateral line and the median line of the back. The head is 

 contained 6^ times in the length, and 1^ times in the greatest depth. 



