502 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



obsolete distally ; the bases of the plates are bounded on each side by 

 one or two scales. The infraorbital ridge is covered by two series of 

 scales behind the middle of orbit. The ridges of the head are cov- 

 ered by rather strong scales, mostly close-set with spinules; the 

 occipital and postorbital ridges, together with the posterior half of 

 the supraorbital ridge, are covered by strong scales bearing a few 

 spinous keels directed backward; the scales on the median rostral 

 ridge are oval or subquadrate in outline, and are armed by several 

 series of spinules radiating in all directions from near the center 

 of each scale. The occipital scute is provided with a strong median 

 keel, and with two (one to several) carinae on each side; the 

 median scute is preceded on each side by a weaker one; a similar 

 scute is located just above the origin of the lateral line. The three 

 to five rows of scales covering the region between the occipital ridges 

 are armed by several high, divergent, serrated ridges. The supra- 

 narial and medial rostral ridge scales are each bounded by scales in 

 single series, separated from each other by a narrow groove; this 

 groove widens forward and merges into a rather wide anterolateral 

 groove, which, though parallel with the infraorbital ridge, is sepa- 

 rated from it by a series of prickly scales; this naked area in the 

 young occupies most of the anterolateral region of the snout, but in 

 the largest specimens is reduced to a narrow groove. Below the orbit 

 and in areas extending backward thence to the preopercular ridge, 

 and forward to the nasal fossa, the scales are reduced in size and 

 spination; the scales between the occipital and infraorbital ridges 

 are otherwise similar to those of the body; the median of the three 

 main series of scales between the occipital and postorbital ridges is 

 slightly enlarged. The nasal fossa and the underside of the head are 

 completely naked in all specimens. 



Base of first dorsal, 1.9 (1.3 to 2.2) in interdorsal space, about 

 half postorbital length of the head; the second dorsal fin is weak 

 anteriorly. The outer ventral ray is filamentous; it enters 2.85 (2.4 

 to 3.2) times into the head"; the second ventral ray extends to the 

 anus. The anal fin is inserted a little in advance of the second 

 dorsal. 



Color in alcohol, light brown, with silvery reflections on the lower 

 sides; the head is lighter in general, but dusky on the opercles. 

 Other specimens are very pale brownish on the trunk and tail and 

 whitish on the head. The second dorsal fin is light; the filament 

 of the outer ventral ray is whitish; the other fins are dusky, quite 

 light in the more faintly colored specimens. The lining of the 

 buccal cavity is dark, becoming lighter toward the gape in some 

 specimens; that of the branchial cavity is blackish, with an abrupt 

 whitish margin along the opercular and branchiostegal membranes; 

 the parietal peritoneum is purplish or brownish black. 



