510 MR. C. TATE REGAN ON THE 
from the caudal equal to } the length of the middle rays of that fin; adipose fin 
represented by a membrane connecting the spine posteriorly to the caudal peduncle. 
Distance from tip of snout to base of first dorsal ray 24 times in the total length, from 
base of last anal ray to caudal 6} times. Greyish; caudal with some dark spots. 
Total length §2 mm. 
A single specimen from Villeta, Colombia, 3500 feet ; collected by Mr. Kay Thomson. 
2, ARGES BOULENGERI, sp. 2. 
Slygogenes humboldtii (non Swainson) Bouleng. Proce. Zool. Soc. 1887, p. 276, pl. xxi. fig. 2. 
Y999 5 P P g 
Length of head about 533 times in the total length. Interocular width much less 
than the distance from eye to posterior nostril, about 5 times in the length of head. 
Lateral teeth of the outer series of the preemaxillaries unicuspid, median teeth bicuspid ; 
mandibulary teeth bicuspid ; barbel extending to gill-opening. First dorsal ray nearly 
equal to the length of head; pectoral spine extending to posterior 3 of ventral ; 
ventrals originating well in advance of the dorsal, extending 3 of the distance from 
their base to the anal opening; spine of adipose fin well developed, freely movable, 
inserted at a distance from the caudal equal to 2 the length of the middle rays of that 
fin. Adipose fin represented by a membrane connecting the spine posteriorly to the 
caudal peduncle. Distance from the tip of snout to the base of first dorsal ray 
21-22 times in the total length, from the base of last anal ray to the caudal 5} times. 
Brownish ; dorsal with some dark spots on the rays; caudal with dark spots forming 
3-4 cross-bars. 
Total length 70 mm. 
Three specimens from Canelos, Ecuador, collected by Mr. C. Buckley. 
3. ARGES GUENTHERI. (Plate XXI. fig. 2.) 
Stygoyenes guentheri Bouleng. Ann. Mag. Nat. Hist. (5) xix. 1887, p. 348. 
Cyclopium guentheri Vigenm. & Kigenm. Occ. Pap. Cal. Ac. i. 1890, p. 350. 
Length of head 53-53 3 
3 times in the total length. Interocular width 3}—52 times in 
the length of head and nearly equal to the distance from eye to posterior nostril. 
Outer series of teeth of the preemaxillaries more or less club-shaped, with a pointed 
lateral cusp, which is smaller and nearer the base in the lateral teeth than in the 
median ; mandibulary teeth bicuspid; barbel extending $—3 of the distance from its 
base to the gill-opening. First dorsal ray equal to 3 the length of head; pectoral 
spine extending to middle of ventral; ventrals originating below the first dorsal ray, 
extending to or beyond the anal opening; spine of adipose fin well developed, freely 
movable, inserted at a distance from the caudal equal to $-4 the length of the middle 
rays of that fin. Adipose fin represented by a membrane connecting the spine 
posteriorly to the caudal peduncle. Distance from tip of snout to base of first dorsal 
