482 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



preceding series of species. The orbit is small: 3.8 (4.1) in the 

 head; 1.75 (1.85) in snout; 1.15 (1.25) in postorbital. The least 

 interorbital width is contained 1.4 (1.5) times in the postorbital; 

 least suborbital width, 2.2 (2.4) times. The upper jaw (4.5 and 

 4.8 in head) extends just a little beyond the vertical from the 

 hinder margin of the pupil ; the teeth of the premaxillary are 

 somewhat enlarged in an outer series. The barbel is short and 

 very slender, 6 (5) in the postorbital; 6 branchiostegals ; fold of 

 gill-membrane very narrow. 



The anus is located immediately before the anal fin, well behind 

 the vertical from the origin of the second dorsal. Its distance from 

 the base of the outer ventral ray is notably longer than either the 

 distance between the ventral and the isthmus or the postorbital 

 length of the head, and is contained 2.6 times in the head; the dis- 

 tance between the ventral fin and the isthmus is equal to the length 

 of the orbit. The anus is preceded by a small scaleless black area, 

 from which a black line extends forward to the oval ventral fossa, 

 which is covered by very thin, smooth scales, and is located just 

 anterior to the ventral fins; the fossa is one-third as long as the 

 postorbital ; the distance from the center of anus to the front of the 

 fossa is half as great as the length of the head. Distance between 

 outer ventral ray and isthmus, 1.25 in postorbital. 



Twenty-one pyloric caeca, shorter than the orbit (in paratype). 



The scales are well imbricate and of medium size; 5 (or 5|) in 

 a series between the front of the second dorsal base and the lateral 

 line (excluding the lateral line scales). Each scale of the body bears 

 5 to 7 poorly developed, slightly divergent carinae, which are armed 

 with six (or fewer) spinules near the middle of the scale, where 

 they are strongest and most numerous ; these spinules are sharp and 

 slender, and are directed backward; the last ones project beyond 

 the margin of the scale. The spinules on the scales of the head are 

 in general similar to those of the body, but are strengthened moder- 

 ately on the supraorbital, postorbital, and occipital ridges; those on 

 the snout and on the infraorbital ridge are characteristically small 

 and suberect. The long, sharp dorsoterminal plate is armed by scat- 

 tered spinules above, and by a marginal series (the strongest) on 

 each side; the ventroterminal plate is armed by five series of spi- 

 nules; the bases of the terminal plates are bounded by the first two 

 scales of the 9 to 11 which cover the ethmoid region of the infra- 

 orbital ridge; the preorbital region of the ridge is covered by 14 to 

 17 scales in a single series, while the preopercular and suborbital 

 regions, behind the posterior margin of the pupil, are covered by 

 a double series; from this double series there extends forward, be- 

 tween the scales of the ridge and the eye, a diagnostic row of modi- 

 fied scales bearing two strong series of spinules. The median ros- 



