2762 Bulletin //, United States National Museum. 



voraer bluntly conical. Gill membranes broadly united, meeting in an 

 angle, joined to the isthmus, but with a free margin; gill rakers 9 + 15. 

 Distance of dorsal from end of snout 2f in the length. Dorsal spine gran- 

 ular on sides and in front, about \ the length of the head in height; 

 distance of the adipose fin from the dorsal 3^ in the length, the height of 

 the adipose fin about 2 in its length, which is contained 2f in the length 

 of the head. Caudal deeply forked, 5 in the length ; anterior f of the 

 anal strongly convex, the posterior \ slightly emarginate, the highest ray 

 about 2 in head. Ventrals reaching to anal, about 2 in head, their dis- 

 tance behind the dorsal equal to the length of dorsal and | the dorsal 

 plate; pectoral spine granulose on sides, the outer margin with a series 

 of larger granules which become recurved notches toward the tip, the 

 inner edge with recurved hooks, its height If in the length of the head ; 

 a small pectoral pore; no evident series of vertical pores. Bluish gray 

 above, becoming white below; the fins brownish with dots. Descrip- 

 tion from the type of Ariits alatus, .68 m. long, from Panama; collected by 

 Dr. Steindachner. (Eigenmann & Eigenmanu, Nematognathi, 61.) 



Selenaspis dowii is thus characterized by Jordan & Gilbert:* Head 4 

 (4 with caudal) ; depth 6 (7*) ; width of head 5. D. I, 8 ; A. 4, 12. Length 

 (29529, U. S. Nat. Mus.) 10 inches. Body elongate, narrow, and slender, 

 the caudal peduncle If in head. Head low and narrow, tapering ante- 

 riorly, the snout subtruncate. Eye small, 7 in head, placed rather high; 

 interorbital space little arched, with ridges and depressions, 2f in head; 

 snout 3f in head; breadth of mouth 2^ in head. Mouth moderate, with 

 thinnish lips; teeth villiform, bluntish; vomerine teeth forming 2 small- 

 ish, rounded patches, separated by a moderate interspace; each patch 

 confluent with the neighboring palatine patch, which is rounded and 

 rather large ; the suture marked by a constriction ; palatine bands with- 

 out backward prolongation ; premaxillary band of teeth broad. Barbels 

 very long; maxillary barbel extending well beyond tip of pectoral fin; 

 outer mental barbel reaching well past front of pectoral; inner 2f in head. 

 Dorsal shield comparatively large, not distinctly crescent-shaped, its 

 divisions produced backward, their length about twice the length of the 

 shield on the median line; anterior margin with 2 emarginations, the 

 point fitting into an emargination of the occipital process; dorsal shield 

 without keel. Occipital process very broad and short, its edges nearly 

 straight, its breadth at base considerably greater than its length; its 

 median line with a rather low keel. Fontauel broad and very short, 

 ending obtusely at a point not far behind eye, the distance from this 

 point to tip of snout 1 in its distance from base of dorsal; each side of 

 fontauel with a conspicuous smooth ridge, the 2 ridges converging 

 anteriorly; shields of head rather finely granulated, few of the granula- 

 tions forming lines, none of them extending farther forward than posterior 

 margin of eye. Opercle striate. Gill membranes meeting below in a sharp 

 angle, forming a rather broad fold across isthmus. Dorsal spine very 

 short, its length a trifle less than pectoral spine, 2J in head. Axillary 

 pore obsolete. Humeral process granulated, rather narrowly triangular, a 



*Bull. U. S. Fish Comm., II, 1882, 50. 



