498 PROCEEDINGS OF THE ACADEMY OF [Sept., 



maxillary and lateral mandibular teeth, absent in young. Maxillary 

 long and slender in adult, much shorter in young. Mandible articu- 

 lated well posteriorly, or below hind eye edge in adult, and in young 

 articulated a little anterior. Nostrils close together, separated by 

 valve only. Gill-opening wide, membranes free from isthmus and 

 largely separated. Rakers lanceolate. Scales all cycloid, well 

 exposed, parallel with 1. 1. above and below, though latter also 

 oblique. Anal with narrow scaly area basally, and scales on caudal 

 base not extending far out on fin. L. 1. incomplete, not extending 

 beyond dorsal base. Dorsal median, base short, and rays greatly 

 elevated. Anal begins after dorsal base, its own base long, and 

 front rays elevated. Caudal well forked. Pectoral almost reaches 

 ventral. Ventral inserted before dorsal, reaches anal. 



A single species, small fishes in the mountain streams of western 

 Ecuador. 



(Named for Mr. Samuel N. Rhoads, in slight recognition of his 

 ability as a naturalist and explorer.) 

 Rhoadsia altipinna sp. nov. Fig. 2. 



Head 3f; depth 2|; D. n, 9; A. iv, 24; P. i, 12; V. i, 7; scales 

 in 1. 1. 38 to caudal base, of which 16 anteriorly with tubes; 4 scales 

 in horizontal series medianly on caudal base; 9 scales above 1. 1. 

 to dorsal origin; 11 scales below 1. 1. to ventral origin; 21 scales in 

 vertical series between anal origin and last dorsal ray base; 22 

 predorsal scales; head width 2 in its length; head depth at occiput 

 1|; snout 2f ; eye 4f ; maxillary 1^; mandible If; interorbital 2f ; 

 dorsal base If; least depth of caudal peduncle 2f ; adipose fin length 

 3; fourth branched anal ray If; pectoral If; ventral 1^. 



Body deep, well compressed, form elongately ovoid, and lower 

 profile a little more evenly convex than upper. Owing to slope 

 down posteriorly of dorsal base upper profile appears a little more 

 bulging anteriorly as compared with lower profile. Greatest body 

 depth at dorsal origin. Predorsal region trenchant, and postdorsal 

 region narrowly convex. Behind adipose fin, just before and over 

 anterior rudimentary caudal rays edge becomes trenchant. Breast 

 and preventral region narrowly constricted, though with convex 

 edge. Postventral region narrowly constricted, though scarcely 

 trenchant. Postanal region similar, except edge becoming slightly 

 trenchant over anterior rudimentary rays. Caudal peduncle well 

 compressed, and its least depth about equals its length. 



Head moderate, well compressed, flattened sides slightly approxi- 

 mated below and upper and lower surfaces evenly convex. Profiles 



