56 PKOCEEDINGS OF UNITED STtATES NATIONAL MUSEUM. 



Metliterraneau fauna. The species is dedicated to the distinguislied Sec- 

 retary of the Smithsonian Institution. 



DiAGTv^osis. — Bodj- comi3aratively elongate, somewhat compressed, its 

 greatest height, at a point midway between pectorals and A^entral inser- 

 tions, contained 5^- times in its length to the origin of the middle caudal 

 rays, its greatest width equal to one-tenth of total length, the least 

 height of tail contained 11 times in length of body. 



Scales large, thin, oblong, triangular at the free end, those at the 

 base of the anal fin having the free end more produced than the others. 

 Sixty-five scales in the lateral line, seven rows between it and the origin 

 of the dorsal, eleven between that of the anal and the lateral line. Scales 

 extend for a short distance upon the bases of the dorsal and anal fins. 



Head moderately compressed, snout subconical, the lower jaw in- 

 cluded within the jipper when the mouth is closed. The length of the 

 head is contained 4i times in length of body, slightly exceeding twice 

 the length of the lower jaw. Width of the head equal to the length of 

 the operculum and very slightly less than that of the upper jaw. Width 

 of interorbital area half of the least height of tail. Length of snout 

 half that of the mandible, which is one-ninth of the total length. Diam- 

 eter of orbit equal to length of snout. 



Dorsal inserted directly above the vent, slightly in advance of the 

 anal and at a distance from the snout nearly equal to two-thirds of the 

 total length of the body. 



Length of longest ray of dorsal one-half that of the postorbital por- 

 tion of the head. The distance of the anal from the snout is almost three 

 times the length of the head, its first ray being about under the fourth 

 i-ay of the dorsal. Its length of base is greater than that of the dorsal 

 by one-fifth of the length of the latter; its longest ray slightlj^ exceeds 

 tbe longest of the dorsal. 



Middle caudal rays equal in length to longest ray of anal, the ex- 

 ternal rays somewhat more than twice as long. 



Distance of pectoral from snout three times as great as the least height 

 of the tail ; its length one-tenth of total length and equal to width of 

 body, reaching to ninth row of scales. 



Distance of ventral from snout equal to twice the length of the head, 

 its length slightly greater than that of middle caudal rays. 



lladial formula: B.VL D. 22. A. 25. C. 10. P. 12. AM, 9. Csec. 

 Pyl. 15. 



Teeth on the intermaxillaries, mandible, and palatines. 



Color. — Uniform indigo-blue, 

 mouth and the gill-membranes. 



