040 ZOOLOGY— FISHES. 



NEMATOGNATHI. 



AMIURUS NEBULOSUS, Les. 

 Amiurus nebulosus, Lesueur, Cope, Proc. Am. Phil. Soc. Phila., 1S70, 4S5-4SG. 



A specimen resembling those described by Professor Gill, from Min- 

 nesota, as A. dbesus, which we regard as a variety of the common eastern 

 "catfish". 



Radii: D. I. 6; A. 17; V. 8. 



Arkansas River, Pueblo, Colo. (Mr. C. E. Aiken). 



PLECTOSPONDYLI. 



PLAGOPTERUS, Cope. 



Pharyngeal teeth, 2.5-4.2 ; raptorial uncinate, without masticatory 

 surface. A terminal maxillary barbel. Scales, none ; lateral line well 

 developed. Dorsal fin with a strong spine composed of two, the posterior 

 received into a longitudinal groove of the anterior. Ventral fins origi- 

 nating (in the type species) a little anterior to the line of the dorsal, attached 

 to the abdomen by a wide basis and length of inner radius. Superior labial 

 fold continued round the end of the muzzle. 



This genus resembles 3Icda, Girard, in the presence of the dorsal spine, 

 the adhesion of the inner border of the ventral fin, and the absence of scales, 

 and differs in the presence of barbels, and the inner dental series being 5-4 

 instead of 4-4. Physiognomy of Hhinichthys. 



PLACOPTERUS ARGENTISSIMUS, Cope. 



Plate XXVI, Figs. 3, 3a. 



Plagopterus arqentissimus, Cope, Proc. Am. Phil. Soc. Phila., 1874, ]30. — Id., Rep. 

 Plagop. & Ichthy. Utah, 1S74, 4. 



This is a small fish, of slender proportions, with a, rather broad head, 

 with slightly depressed muzzle overhanging by a little a horizontal mouth 

 of moderate size. The caudal peduncle is of medium depth, and the caudal 

 tin is deeply forked. The eye is somewhat oval, and enters the length of 

 the side of the head 4.2 times and the interorbital width 1.5 times. The 

 greatest depth (near the ventral tin) enters the total length nearly six times, 



