1894.] ^ ^1- [Cope. 



the .Tutahy in "Western Amazonia. The four specimens of the P. aspilo- 

 gaster before me are from the Jacuhy, Rio Grande do Sul. This species 

 also approximates the F. limosus Eigenm. {Proceeds. Calif. Acad. Sci., 

 1888, pp. 167-8), from the Uraguay R. According to the description 

 tliis species has the occipital plate bordered by a single nuchal instead of 

 by three, and the middle rays of the caudal fin are nearly equal to the 

 length of the head. The postdorsal region should be rounded above and 

 below, whereas it is flattened, and the fins and belly are spotted. In the 

 P. ospilogaster the caudal fin and belly are without markings. 



The Plecostomus virescens Cope (Proceeds. Academy, Philadelphia, 1874, 

 p. 137) was founded on young individuals from Eastern Peru. The Eigen- 

 manns state their inability to locate it in their system of Nematognathi. 

 In their table of the genus Plecostomus (I. c. p. 398) is a section which 

 includes species with the ventral integument more or less scaleless, a 

 character which Boulenger alleges to be more or less untrustworthy. In 

 any case two specimens of the P. virescens of 60 mm. in length have the 

 belly smooth. In one of 70 mm. a few granules appear on the median 

 line of the belly. In one of 92 mm., a band of granules extends from the 

 anus to the coracoid bridge on the middle line spreading and fading out 

 laterally on the belly. Supposing the latter character to be retained to 

 maturity (which is uncertain) the P. virescens differs from the species 

 referred to the section with naked bellies by the Eigenmanns. Disregard- 

 ing the squamation of the belly, the former enters the section which 

 includes the P. hicirrhosus. The 1.1. is 26-7. Superciliary borders a little 

 raised. The triangular part of the occipital bone is bordered by two 

 scuta on each side, and one scutum which touches the apex, and none of 

 them are angulated. Body scales not keeled. The base of the dorsal 

 equals its length from the adipose fin. A few small spines at the inferior 

 opercular angle. Head and body unspotted. All the fins spotted. Appa- 

 rently nearest the P. tillarsii Luelken. 



Callichthys tamoata Linn. 



CORYDORAS PALEATUS Jcnyns. C. mnrmoratus Steind., Denkschr. 

 K. Akad. Wien, 1879 (see PI. v. Fig. 1) ; good figure. 

 About sixty specimens, varying in length from 35 mm. to 70 mm. I 

 liave examined about fifty of these in order to ascertain whether there is 

 any variation in the degree of extension of the coracoid bones over tlie 

 pectoral region. There is no variation, that of each side remaining widely 

 separated from the corresponding one of the other side in all the speci- 

 mens. Not having met with any variation in any of the species in this 

 respect, I distinguished the species where the pectoral region is enclosed 

 below by the coracoids, as a distinct genus, retaining for it the name 

 Corydoras, and naming the series with naked breast, Gastrodermus.* Ac- 

 cording to Eigenmann,t the type of Corydoras, C. punctatus L., possesses 



• Proceeds. Amer. Philos. Soc, 1878, p. C81. 



t Revision of S. Amer. Nematognathi, 1890, p. 4C5. 



