THE AMERICAN TETRAGONOPTERINAE. 177 
Origin of the dorsal nearly the length of the eye nearer to the caudal than 
to the snout, the penultimate ray 2.5 in the longest which is 4 in the length. 
Anal origin on the vertical from the fifth or sixth dorsal ray. Anal emarginate. 
Caudal equal to the head in length. Ventrals on the vertical half the length 
of the dorsal basis in front of origin of dorsal. Ventrals reaching the base of 
the fifth anal ray; pectorals reaching to third scale beyond origin of the 
ventrals. 
A triangular black spot covering all but the extreme base of the proximal 
half of the anterior six or seven dorsal rays, widest anteriorly. Membranes 
especially at the tip of anal with numerous chromatophores, chromatophores 
scattered sparingly over all the fins and sides excepting the part over the body- 
cavity. No humeral or caudal spot. Preopercle with some silvery iridescence. 
2. HYPHESSOBRYCON MILLERI Durbin. 
Plate 24, fig. 2. 
Hemigrammus compressus M1tuEr, Bull. Amer. mus. nat. hist., 1907, 28, p. 101 (Los Amates). 
Hyphessobrycon compressus milleri DurBin, Bull. M. C. Z., 1908, 52, p. 100; Eraenmann, Rept. Prince- 
ton univ. exped. Patagonia, 1910, 3, p. 436. 
Hapitrat.— Guatemala. 
One specimen 112551. Type 40 mm. Los Amates, Guatemala Miller 
Very closely related to H. compressus from which it may be distinguished 
by having the entire dorsal dark. Anal membranes except, in the anal lobe, 
black. Opercle deeply incised behind, maxillary less than the eye; naked margin 
around the second suborbital not more than half the width of the bone. 
Head 3.25; depth 2.5; D. 11; A. 25; scales 8-45 to 48-7, eye 3 in the 
head, interorbital equal to the eye, 3 in the head. 
Like H. compressus in shape and scaling of preventral, postventral, and 
predorsal regions, relative length and size of occipital process, frontal, and parie- 
tal fontanels. Interorbital slightly more convex. Second suborbital small, 
about half as wide as the eye, but more than twice as wide as its naked margins. 
Opercle deeply incised behind. Maxillary shorter than the eye; mandible 
1.2 times the eye. Snout a little less than half the eye. Teeth as in H. com- 
pressus. 
Gill-rakers 9 + 10, slender, serrate on one side only. 
Seales not different from those of H. compressus, except that the lateral 
line is very slightly decurved. 
