260 PROCEEDINGS OF THE ACADEMY OP 



and a vertical bar at base of caudal fin black. Total length 

 •048 m.; to dorsal .0175; to anal .03; to basis caudal .039. The 

 opercle of one of the specimens is white and smooth, cf another 

 punctate-rugose and 3'ellow. 



IGUANODECTES, Cope, gen. nov. 



Dorsal fin originating in advance of ventrals, anal elongate. 

 Branchiostegal membranes united across, but not with, isthmus. 

 Teeth in two series in the premaxillary, none in the maxillary, and 

 one row in the mandible. They are fixed, but have contracted 

 fangs, and broad, flat, subequally denticulate crowns, and those of 

 the mandible stand out from the dentary bones all round. Teeth 

 of the outer row verj^ few, minute. Caudal fin furcate. 



This genus is allied to Tetragonopterus, but the dentition is 

 much weaker, approaching that of the Schizodon ; the union of 

 the branchiostegal membranes is seen in Lseniolyta m. In the only 

 species there are but two minute teeth of the outer premaxillary 

 row. Tlie other teeth are fan-shaped and smooth, and in contact, 

 so as to form an uninterrupted series. In Tetragonopterus the 

 fangs are strong, not contracted, and the crowns are ridged. 



IGUANODECTES TENUIS, Cope, gp. nov. 



Slender, the depth entering the length (without caudal) 5,5 

 times, length of head 4.33 times in the same. Eadii D. 12 ; A. 36 ; 

 V. 9, P. 13. Pectoral reaching ventral and ventral anal. Orbit 

 3.2 times in head, equal interorbital width, less than length of 

 muzzle. L. tr. al. A. i. 11-12. Caudal furcate. Distance from 

 base dorsal to base caudal equal from former to pupil of eye. 

 Color pale, a silver band along side ; base of caudal blackish. 

 Total length .059 m. ; to basis dorsal .027 ; to basis anal .0275. 



APHYOCHARAX PUSILLUS, Gtkr. 

 Proc. Zool. Soc. Lond., 18G8, 245. 

 Fins bright red in life. 



TETRAGONOPTERUS CHALCEUS, Artedi. 

 Agass. Cuv. Val., Gthr. Catal. v. 320. 



TETRAGONOPTERUS BARTLETTII, Gthr. 

 Am. Magaz. Nat. Hist., 18G6, 30. 



[January 16, 



