1903.] NATURAL SCIENCES OF PHILADELPHIA. 507 



Distance of dorsal spine from tip of snout 2 in length; the spine If 

 in head; roughened behind; first 4-5 rays higher than the spine. 



Pectoral spine IJ-lf in head, outer side smooth, inner rougliened. 



Caudal deeply forked, 2^^-3 in length, its dorsal lol)e slightly longer. 



Color yellowish-brown changing to white below; a light middorsal 

 band, extending from fontanel to base of caudal. At the base of 

 the dorsal this band widens into a dark spot. A lateral band starts at 

 the base of the caudal and widens as it passes forward, to end in a more 

 or less distinct lateral spot. All the fins are plain. 



Three of the specimens (260) are darker. The lateral band is not 

 distinct from the middorsal. The top and sides of the head, the dorsal 

 and caudal fins are tinged with dark. 



Lat. plates ^-.-v^^-S. jy i j.g. ^ j.g. y q. p j ^.g 



These specimens, measuring between 15-60 mm., differ from the 

 adult in having the eye H in the snout, 3 in the head, and 1^ in the 

 interorbital. Depth 2h, head 2f, dorsal spine If in head, pectoral 

 spine 1-i- in head. 



This species stands nearest to nattereri, from which it differs in 

 having the eye smaller, snout more conical and in the shape of the 

 dorsal fin. 

 35. Corydoras aurofrenatus sp. nov. 



Type Xo. 9,891, one specimen (235). 55 mm. Aguada, near Arroyo 

 Trementina. December, 1900. 



Body elongate, fins and head small. Profile obtusely angled between 

 the nares, steep from the nares to the snout. Fontanel very elongate, 

 extending to the base of the occipital process. Width of occipital 1-^ 

 in its length. 



Eye 2 in snout, 1^ in interorl)ital, 3^ in head. 



Snout conical, somewhat compressed. Posterior margin of ojjercle 

 slanting downward and forward. Distance from upper end of gill- 

 opening to eye equal to diameter of eye. Labial barbel reaches gill- 

 opening; maxillary barbel slightly shorter. Mental barbels equidis- 

 tant from each other and the angles of the mouth. 



Coracoid process scarcely encroaching on the breast or belly. 



Three to four azygos plates before the adipose. 



Distance of dorsal spine 2\ in length; its height IJ in length of head. 

 First two dorsal rays exceed the spine. A band of spines, similar to 

 those on the plates, along the anterior edge of the spine. A similar 

 band but narrower on each lateral edge of the spine; the posterior 

 edge roughened. Caudal forked for half its length; about 2§ in the 

 length. 



