254 Field Museum of Natural History — Zoology, Vol. X. 



in head; origin of dorsal slightly nearer adipose than tip of snout; 

 adipose well developed, inserted a little nearer base of caudal than base 

 of last dorsal ray; caudal fin with an oblique or slightly concave margin, 

 the lower rays the longest; anal fin small, its origin behind last ray of 

 dorsal; ventral fins reaching well past origin of anal; pectoral fins very 

 long, reaching beyond the middle of ventrals, longer than head. 



Color uniform dark above; ventral surface of head and abdomen 

 brownish, with or without bluish spots. Fins with dark spots on the 

 rays and pale ones on the interradial membranes, sometimes forming 

 wavy bars on the fins. The spots most distinct in our largest specimens. 



There are 31 specimens in the Panama collection, ranging from 35 to 

 235 mm. in length. All are from the Rio Tuyra Basin. 



We have for comparison 4 specimens (paratypes) from Cartago, 

 Atlantic slope of Colombia, of the rather closely related species, L. 

 caucanus Eigenmann (Indiana University Studies, No. 16, 191 2, 11). 

 The latter differs from L. planiceps in the slightly deeper body, lower 

 dorsal and pectoral fins, in the shape of the first median scute behind 

 occipital, and in color. 



10. Genus Leptoancistrus gen. nov. 



Type Acanihicus canensis Meek & Hildebrand, Field Mus. Nat. Hist. 



Pub., Zool. Ser., X, 1913, 80. 



Body anteriorly low and broad; snout granular to its margin, bear- 

 ing short bristles; head and body without prominent ridges or carina- 

 tions; interopercle freely movable, bearing spines which cannot be 

 retracted under the opercle ; premaxillaries and dentaries of about equal 

 length; the mandibular ramus nearly equal to interorbital width; the 

 first scute of lower lateral series separating the second scute from the 

 temporal plate; adipose and anal fins wanting. 



11. Leptoancistrus canensis (Meek & Hildebrand). 



Acanihicus canensis Meek & Hildebrand, Field Mus. Nat. Hist. Pub., 



Zool. Ser., X, 1913, 80 (Rio Cana, Cana, Panama). 



Head 2.53 to 2.83; depth 5.5 to 6.45; D. I, 8; lateral scutes 22 or 23. 



Body very broad anteriorly, more than twice as wide as deep; 

 caudal peduncle posteriorly compressed; head low and very broad; 

 snout broadly semicircular, granular to the margin, the latter bearing 

 short bristles, its length 1.45 to 1.7 in head; eye very small, 7.5 to 10; 

 interorbital 3 to 3.63; mouth wide; the lips expanded, the margin of the 

 upper following margin of snout; the margin of lower lip fringed, with a 

 minute barbel opposite angle of mouth; teeth slender, bifid, curved 



