218 PROCEEDINGS OF THE ACADEMY OP 



scending behind from the middle of the dorsal fin. Radii D. I. 

 11, L, without adipose portion ; C. 14 ; A. 8 ; V. short, 6 ; P. I. 9. 

 Dorsal spine moderate, serrate behind and smooth before, pectoral 

 stronger, finely but strongly serrate behind, smooth in front ; it 

 extends to or a little beyond the middle of the ventral in all our 

 specimens. Length, three inches ; depth, one inch. 



Color of body and sides above, with sides of head, metallic 

 blue ; below, yellowish. Fins unspotted. 



This elegant species appears to be very common in the tributa- 

 ries of the Ambyiacu. 



BEOCHIS DIPTERTIS, Cope, sp. nov. 



This species is represented by a single specimen, which diflfers in 

 several points from the type of the genus. These are: 1st, the 

 existence of a w^ell-developed adipose membrane to the adipose 

 fin ; 2d, the existence of only ten rays in the first dorsal fin ; 3d, 

 the thick attached inferior lip with two median beards. The 

 lateral shield of the muzzle is more completely united with the 

 surface of the ethmoid than in similar specimens of the B. 

 coeruleus, but not more so than in larger specimens. Scuta 24 

 above. Pectoral and dorsal spines serrate within. Color and 

 proportions as in B. coeruleus, the added adipose fin having a 

 black border behind. 



The characters of seven specimens of the type species are con- 

 stantly dilferent from this one. 



CORYDOKAS, Lacep., 

 Differs from Callichthys in the prolongation of the supraoccipital 

 shield upwards between the lateral shields to near the base of the 

 dorsal ray, and in the possession of strong dorsal and pectoral 

 spines. 



The species of this genus are referred to a section of Callich- 

 thys by Dr. Giinther, which he characterizes by the compressed 

 form of the head. I think they constitute a natural genus char- 

 acterized as above, and would admit species having the above 

 peculiarities into it, no matter what the form of the head. The 

 new species here described, however, agree with those already 

 known in this compression of the head and body. The genus 

 differs from Brochis in the non-shielding of the intercoracoid re- 



[February 13, 



