THE AMERICAN TETRAGONOPTERINAE. 117 
3. KNoDUS MOENKHAUSII (Eigenmann and Kennedy). 
Plate 10, fig. 3. 
Poecilurichthys moenkhausti E1iGeENMANN & Krnnepy, Proc. Acad. nat. sci. Phil., 1903, p. 522 (Arroyo 
Trementina). 
Bryconamericus moenkhausii E1GENMANN, Rept. Princeton univ. exped. Patagonia, 1910, 3, p. 434. 
Hasirat.— Paraguay; Upper Amazon. 
Specimens examined. 
Catalogue Number of 
number specimens Length in mm. Locality Collector 
10001 I. 1 Near Arroyo 
10002 I. W | 29-43 Trementina, Anisits 
10003 I. } Paraguay 
20760 8! 40-45 Tabatinga Bourget 
Head usually 4 (rarely 4.3); depth 3.5-3.75; D. 10, counting everything; 
A. 22-24; scales 5-39-3.5 or 4, rarely 38 scales in the lateral line; eye 2.52.66, 
equal to interorbital. 
Slender, little compressed, the width about 2 in the depth; dorsal and 
ventral profiles equally curved, without elevations or depressions; preventral 
area rounded, postventral compressed; predorsal area narrowly rounded, 
without a keel, with a median series of (about 12) scales between the occipital 
process and the dorsal. 
Occipital process about as broad as long, its length equals one eighth of 
the distance from its base to the dorsal, bordered on the side by one or two 
scales; interorbital flattish; frontal fontanel as wide as, and half as long as, the 
parietal; second suborbital covering the entire cheek to the lower opercular limb; 
maxillary slender, its anterior margin not conspicuously arched, its length not 
1 These eight have the following characters: 
Eye in) Mandible in Teeth of Teeth of 
the length the length the pre- the 
D. A. Seales Head Depth of head of head maxillary maxillary 
10 22 5-38-? 4 3.5 2.66 3.54 4&4 5 
10 24 ? 4.3 3.75 4&4 3 
10 22 5-39-? 4 3.5 2.5 3+ 4&4 3 
10 22 5-39-3.5 4. 3.75 2.5 3+ 4&4 3 
10 24 5-38-4 4.2 3.5 2.5 3+ 5&4 1 
10 22 5-39-3.5 4 3.6 2.6 3+ 4&4 4 
10 24 5-39-3.5 4 3.7 2.5 3+ 5&4 1 
10 23 ? 4 3.5 2.6 3 4&4 3 
