NATURAL SCIENCES OF PHILADELPHIA. 269 



than interorbital space. Yeutral fin originating opposite front of 

 dorsal ; not reacliing vent ; pectoral reaching ventral. Bones of 

 head striate. Caudal fin openly emarginate. Color pale fawn- 

 color above, below silvery; four longitudinal series of round 

 black spots above lateral line ; several scattered spots below it. 

 Opercular apparatus brilliantly colored ; upper part of preoper- 

 culum and orbital bones green ; middle golden, lower part purple 

 and violet. Operculum purple above, vermilion below; interoper- 

 culum vermilion; anal fin the same; caudal brown, edged with 

 pale yellow centre. 



Total length .104 m.; to dorsal .0535 ; to ventral .0475; to anal 

 .0615; to caudal .084. 



This brilliant species is especially peculiar in the number of its 

 abdomino-thoracic dentations. 



From the Ambyiacu. 



SERKASALMO ^SOPTJS, Cope, sp. nov. 



Radii D. 16; A. 32; Y. 7; pectoral falcate reaching basis of 

 ventral. Form short, deep, dorsal curve greater than abdominal. 

 Depth 1.66 times in length without caudal, length of head three 

 times in the same. Scales 47-83-36; ventral spines 31.. Muzzle 

 very short, onl}' half as long as diameter of bony orbit, which is 

 contained four times in the length of the head, and twice in the in- 

 terorbital space. Latter convex transversely. Lateral line slightly 

 decurved in the middle. Dorsal fin nearer the base of the caudal 

 (first fulcrum) than the end of the muzzle, by the length of the 

 latter and half the diameter of the orbit. 



Color bright yellow, unspotted, except a shade behind the epi- 

 clavicle. Caudal fin with a yellow margin and black band within 

 it ; anal fin with a dark margin. 



Total length .147 m. ; to dorsal fin .075; to ventral .065; to 

 anal .088; depth at orbit .028; at first anal ray .073. 



From the Marailon between the mouth of the Rio N'egro, Brazil, 

 and the Huallaga, Peru. Robert Perkins. 



SILURID^. 



PSEUDORHAMDIA PISCTARIX, Cope. 



Proceed. Am. Philos. Soc, 1870, 5G9. 



This species presents slight difierences in the size of the orbits 

 and relative slenderness of the body, not dependent on age. 

 1872.] 



