252 Fretp Museum or Naturat History — Zoétocy, Vor. X. 
which vary in size, shape and number among individuals; fins all brown- 
ish green with pale green spots. 
The Panama collection contains 56 specimens, ranging from 45 to 
255mm.inlength. Fifty-four of these are from the Rio Chagres Basin. 
The other two were taken in the Rio Chorrera, a small stream on the 
Pacific slope west of Panama City. 
Habitat: Rio Chagres and Rio Chorrera, Panama. 
9. Ancistrus spinosus sp. nov. 
Type No. 8942, F. M. N. H.; length 135 mm.; Rio Calobre, 
tributary of the Rio Bayano, Panama. 
Head 2.65 to 2.77; depth 4.6 to 4.7; D. I, 7; A. I, 4; lateral scutes 24. 
Body broad anteriorly; caudal peduncle posteriorly compressed; 
head broad; interorbital width nearly equal to the depth of body, 1.95 
in head; snout obtuse, the naked portion narrow in the female and with “ 
only 4 small tentacles, much wider in the male with a fringe of tentacles 
along the margin and a V-shaped patch on the upper surface at the tip; 
length of snout 1.63 to 1.7 in head; eye 8.75; mouth wide; the lips 
expanded; the lower lip with a small barbel, shorter than eye, on its 
lateral margin; the premaxillaries and dentaries equal in length; man- 
dibular ramus 3.1 to 3.6 in interorbital width; teeth slender, bifid, 
curved inward near the tips; interopercle with from 8 to 12 spines, 
curved outward and forward near the apices, longer in the male than 
in the female; sculpture of head without ridges or carinations; scutes on 
back and sides not carinate, their margins very strongly serrate, espe- 
cially in the male; occipital posteriorly bordered by 3 scutes; the second 
median scute with an evident median suture; 6 scutes between dorsal 
and adipose; 11 or 12 between anal and base of caudal; lower surface of 
head and abdomen naked; dorsal fin very high, the posterior rays when 
deflexed reaching past origin of adipose, the spine 1.15 to 1.2 in head; 
base of dorsal equal to distance from the base of its last ray to base of 
caudal; adipose fin well developed; caudal fin with a nearly straight 
oblique margin, the lower rays the longest; anal fin small, its origin 
slightly behind vertical from base of last ray of dorsal; ventral fins 
reaching well beyond base of anal; pectoral fins very long, reaching to 
or past the middle of ventral, the spine a little longer than the head. 
Color uniform dark above. The male plain brownish below; the 
female with faint pale spots on abdomen; fins in male plain brownish, 
in female with faint pale spots. 
Apparently a rare species. There are at hand only 2 specimens, a 
male and female, respectively 130 and 135 mm. in length. The male 
was taken at the mouth of the Rio Yape, tributary of the Rio Tuyra; 
