1903.] NATURAL SCIENCES OF PHILADELPHIA. 505 



from a small lagoon in Campo Grande, 5 kilos from Asuncion and 

 the Rio Paraguay, differ from the first two in having the posterior mar- 

 gins of the anterior pair of nuchal plates ver}" much rounded. In fact, 

 the posterior border on either side lies for f its length at right angles 

 to the axis of the body. They differ also in being of a uniform dull 

 lead color and in the size of the eye — 6+ in the interorbital. The two 

 specimens differ as follows : 



Specimen a, 21 cm. (c? ?). Pectoral spines as long as head. In this 

 specimen, which is probably a male, the skin along the under side of 

 the pectoral rays is greatly thickened, forming along each ray for f its 

 length a heavy ridge. 



Specimen 6, 18 cm. (? ?). Pectoral spines If in head. 



Key to the Species of Corydoras. 



a. Coracoid processes meeting on median line of anterior portion of 



belly at least. 



b. A dark brown lateral band extending from the occiput backward 



on the upper half of the body; ventral surface and a broad ver- 

 tical band behind the eye light ; caudal without bars, . equcs. 



hb. Greenish, fins and top of head brown ; a dark brown band on caudal. 

 D.I, 9; Lat. pi. H, splendens. 



aa. Coracoid processes nowhere meeting; breast and belly with a 

 median naked area. .^ 



c. Caudal plain. 



d. Body with one or more dusky longitudinal Ixinds ; dorsal fin usually 



spotted. 



e. Coracoid processes moderately expanded, leaving onh- a narrow 



naked area between them; occipital process triangular, pointed 

 at the tip; a dark band extending from the upper caudal lobe 

 forward, one or more longitudinal series of dark spots along the 

 sides, elegans. 



ee. Coracoid process scacely encroaching on breast or belly. A black- 

 ish lateral band extending from the middle caudal rays for- 

 ward. 

 /. Ej'e 2-2J in snout, 4-5 in head, 2-2^ in interorbital. First 4-5 

 dorsal rays as long as the dorsal spine, microps. 



ff. Eye l\ in snout, 4 in head, 2 in the interorbital. First 2 dorsal 

 rays as long as the dorsal spine, nattereri. 



dd. Body without longitudinal bands; dorsal plain. D. I, 7; A. I, 6; 

 P. 1,7-8 ;V. 6. 

 g. Head and dorsal plates deep bronze; ventral plates yellowish; 

 all the fins immaculate; opercle, humeral and nuchal plates 

 iridescent blue ; base of the dorsal fin shorter than the distance 

 between the dorsal and adipose; depth less than \ of total 

 length; eye 4^ in head, more than 2 in the interorbital 

 (Gill), /. .' ■ . ceneus. 



