FISHES OF THE FAMILY LOEIOAEIID^. 317 



from their base to the anal opening, or sometimes nearly to the anal opening. 

 Adipose fin long, moderately developed, without trace of a spine. Distance from 

 tip of snout to base of first dorsal ray 2f times in the total length, from base of last 

 anal ray to caudal 6^-7 times. Greyish ; caudal with some dark spots. 



Total length 88 mm. 



Ten specimens from Eastern Ecuador. 



18. Akges peku anus. 



Arges peruanus Steind. Sitzb. Ak. Wien, lxxii. pt. i. 1875, p. 601, pi. ix. figs. 3-6, and Denkschr. 

 Ak. Wien, xli. 1879, p. 173. 



Length of head 3^-4 times in the total length. Interocular width less than the 

 distance from eye to posterior nostril, 3|-3f times in the length of head. Outer series 

 of teeth of the prsemaxillaries compressed incisors, with the upper edge slightly 

 emarginate, notched ; mandibulary teeth similar ; barbel extending \ the distance 

 from its base to the gill-opening. First dorsal ray equal to § the length of head ; 

 pectoral spine extending to anterior \ of ventral ; ventrals originating below or slightly 

 in advance of the first dorsal ray, extending \- § of the distance from their base to the 

 anal opening ; adipose fin long, low, feebly developed, without trace of spine. Distance 

 from tip of snout to base of first dorsal ray 2^ times in the total length, from the base 

 of last ray of anal to caudal nearly 5 times. Uniform brownish ; fins without spots. . 



Total length 63 mm. 



Four specimens from Amable Maria, Peru. 



19. Arges simoksii, sp. n. (Plate XXI. fig. 9.) 



Length of head 4-4f times in the total length. Interocular width equal to the distance 

 from eye to posterior nostril, 3|-3| times in the length of head. Outer series of teeth 

 of the prsemaxillaries incisors, with straight or notched edges ; mandibulary teeth 

 similar ; barbel extending f-4 of the distance from its base to the gill-opening. First 

 dorsal ray equal to f-f the length of head ; pectoral spine extending to anterior £ of 

 ventral; ventrals originating below the first dorsal ray, extending f-f of the distance 

 from their base to the anal opening ; adipose fin long, low, moderately or well 

 developed, without trace of spine. Distance from tip of snout to base of first dorsal 

 ray 2f-2| times in the total length, from base of last anal ray to caudal 5|-6 times. 

 Body sometimes spotted or marbled with dark brown ; some dark spots on the dorsal. 



Total length 80 mm. 



Five specimens from Huaras, Peru, 10,700 feet, collected by the late Mr. P. 

 O. Simons. 



