ANNOTATED LIST OF THE SPECIES Zilko 
Characidae Gill, 1893, Mem. Acad. Nat. Sci., VI, 131; 
EKigenmann, 1917-1929, Mem. Mus. Comp. Zool., XLII, 17. 
An extensive family, mainly tropical, through the freshwaters of South America 
and Africa. Sealy fishes with adipose dorsal usually; short dorsal, single, without 
spines; barbels and plated areas lacking. Extremely variable in body form, pos- 
sibly polyphyletic, the respective subfamilies having resemblance to other fishes 
in similar habitats. 
First Division—Cheirodontine group of Subfamilies 
Subfamily: CHETRODONTINAE 
Moderately deep-bodied; anal fin long, its origin beneath the last dorsal ray 
and extending almost to the caudal, which is deeply forked; mouth terminal and 
relatively small; cycloid scales of unspecialized type; dentition variable, allied to 
that of various subfamilies. Gregory and Conrad assign this subfamily the place 
nearest the stem of the more specialized forms. 
Genus 92: OTHONOCHEIRODUS Myers 
Othonocheirodus Myers, 1927, Bull. Mus. Comp. Zool., LN VITI, 1, 113. 
Type: Othonocheirodus eigenmanni Myers 
The middle Huallaga 
Like Monotocheirodon differing from Holosthenes, Odontostilbe and Cheirodon 
in the horizontal gape and the naked teeth of the upper jaw; unlike the first-named 
in the great horizontal extent of the maxillary; teeth 6-7; vertical ramus slight, 
scarcely intersecting the line of the mandibular tooth-bases, its end not rounded 
or free; body more compressed. 
239. OTHONOCHEIRODUS EIGENMANNI Mlyers 
Othonocheirodus eigenmanni Myers, 1927, Bull. Mus. Comp. Zool., LX VIII, 1, 114. 
Rio Huallaga at Cayumba rapids 
17674, 17675 (original number 16125), 4, tvpe and paratypes, 38-47 mm., Cayumba rapids, Rio 
Huallaga, Allen, October, 1918. 
Second Division—Tetragonopterine group of Subfamilies 
Subfamily: TETRAGONOPTERINAE 
Characins of oblong form, often elevated considerably; scales of moderate 
size; dentition complete in both jaws; gill-openings wide, the membranes not at- 
tached to the isthmus; nasal openings closely approximated; teeth compressed, 
notched. 
Genus 93: HEMIBRYCON Giinther 
Hemibrycon Giinther, 1864, Cat. Fish. Brit. Mus., V, 318; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 432; 
Bigenmann, 1927, Mem. Mus. Comp. Zool., XLIII, iv, 401. 
