304 PROCEEiDINGS OF THE NATIONAL MUSEUM vol.94 



(83.3; 83.5); distance from snout to origin of anal fin 68.2 (70.7; 72.5); 

 distance from snout to insertion of pelvics 51.3 (49.6; 52.7). 



The following counts were made, respectively: Dorsal rays I, 7 

 (I, 7; I, 7; I, 7); anal I, 3 (I, 3; I, 4; I, 4); pectoral always I, 6 and 

 pelvic always I, 5; number of scutes in lower lateral series 24 (24; 

 24; 24); plates from dorsal to origin of adipose 5 (5; 5; 5); plates from 

 base of anal to base of m.idcaudal fin rays 12 (12; 12; 12); plates in 

 front of dorsal fin 4 (4; 4; 4); nmnber of spines on the interopercle 

 15 (13; 13; 12); nmnber of tentacles at corner of mouth plus marginal 

 series plus those at other corner of mouth 5-f-S-i-5 (0 + 0+0; + + 0; 

 5+8 + 5); for additional counts see table 18. 



Head depressed, snout "with the anterior portion without bony 

 covering, this area much wider in males than m females; the dei-raal 

 cirri on adult males are m.ultifid, especially those in the Y-shaped 

 group near the middorsal line; I can find no tentacles on the snout of 

 females; the preopercular spines are hooked, and the longest are 

 contamed IK to 2 times in the interorbital length; there are three 

 plates bordering the supraoccipital behind, the middle one not divided 

 in the midlme; m addition there are three other plates in front of the 

 dorsal; depressed dorsal fin reaches to base of the long adipose spine 

 thus beyond the platelet in front of this spine but forming part of 

 that fin; none of the plates keeled; belly naked; breast naked; teeth 

 small, very numerous and bind; lips papillate; a small barbel at corners 

 of mouth; pectoral spine on adult male reaches to begmning of second 

 tliird of length of pelvic spine; caudal fin concave in young but a little 

 convex in adults, lower lobe longest; posterior margin of dorsal a 

 little convex. 



Color.- — Dorsal surfaces anterior to dorsal fin with obvious pale 

 spots more or less oblong to squarish, belly with pale, elongate to 

 oblong streaks or spots, some of which join each other to form a loose 

 marbling effect; the pale spots and blotches may be obscure or entirely 

 absent on the young; a black spot at base of membrane between 

 dorsal spine and first soft ray, dorsal fin barred, these numbering 

 four to sLx; other fins similarly barred; tips of upper and lower caudal 

 lobes white; a pale bar across caudal peduncle, more distinct in smaller 

 specimens, at base of caudal fin rays; sides of body more or less with 

 darkish blotches; a somewhat obscure pale oblique bar between rear 

 base of dorsal and adipose fin from back downward across upper 

 sides. 



Remarks. — This new subspecies difi'ers from Ancistrus triradiatus 

 iriradiatus Eigenmann from the upper Orinoco system in having the 

 anal rays about equally I, 3 or I, 4 instead of almost always I, 3; 

 the number of plates from the dorsal fin base to the origin of the adi- 

 pose is usually four (seldom five) in triradiatus while in martini almost 



