478 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



with a free fold. The center of the anus is in advance of its normal 

 position before the origin of the anal fin, the interspace being con- 

 tained 1.4 (1.0 to 2.0) times in the distance between the anus and the 

 base of the outer ventral ray; the latter distance is contained 1.4 

 (1.3 to 2.0) times in the interval between the ventral fin and the isth- 

 mus, or 1.4 (1.3 to 1.8) times in the postorbital length of the head. 



Summarized tabic of proportion of parts of the head. 1 



Orbit in heid 



Orbit in postorbital 



Orbit in snout 



Interorbital in postorbital 



Suborbital in postorbital 



Upper jaw in head 



Barbel in postorbital 



Length of snout in head: 



J 'reocular 



Preoral 



Width of snout in head 



Width of snout at end of ethrmid region of infraorbital ridge, measured 

 into length of snout before that point 



Variation. 



3. 05 to 3. 3 

 0.8 to 1.0 

 to 1.4 

 to 1.5 

 to 2. 25 

 to 4. 65 

 to 5.5 



1.2 

 1.3 

 2.0 

 4.1 

 3.6 



25 to 2. 6 

 4 to 2. 9 



2. 4 to 2. 7 



Type- 

 specimen. 



3.05 



0.8 



1.25 



1.5 



2.0 



4.2 



5.0 



2.5 

 2.9 

 2.55 



1 Measured in each case on 22 specimens, varying in length of head from 30 to 47.5 mm. (excepting case of 

 barbel, measured in 16 specimens). Length of head in type-specimen, 44 mm. 



The scales, especially those on the head, are loosely imbricate; 

 they are larger than in any other species of the notatus group, there 

 being constantly but 4 or 4^ in a series from the origin of the second 

 dorsal to but excluding the scales of the lateral line. The scales of 

 the body are about as rough as in argus or velifer, but. those on the 

 head, especially along the ridges, bear longer and stronger spinules. 

 On each scale of the body there are from 9 to 11 parallel rows of 

 slender and usually long spinules, the arrangement of which is 

 slightly irregular as a result of the obsolescent character of the 

 ridges along which the spinules are usually borne. The last spinule 

 of each series often projects well beyond the margin of the scale. 

 Six to 8 scales, studded with strong conic spinules, bound the eth- 

 moid region of the infraorbital ridge ; there are 8 to 11 scales on the 

 preorbital section of the ridge. There are 8 (6 to 9) scales in a series 

 along the superior rostral ridge; from near the anterior margin of 

 each of these elongate scales there radiate backward several series 

 of fine spinules. This median rostral series is bounded on each side 

 by a single series of rather large scales bearing spinules in several 

 series directed chiefly backward and inward, but not differentiated 

 into two groups as usual in related species. The squamation of the 

 region between the occipital ridges offers diagnostic characters: 

 along the region vertically above the orbit there are three very regu- 

 lar and parallel rows of scales similar to those of the body (in 

 para types smaller scales are sometimes interpolated between these 

 series, rendering the arrangement less regular) ; between the abrupt 



