THE AMERICAN TETRAGONOPTERINAE. 165 
lary three fourths of the eye, about 3.25 in the head. Mandible equal to the 
eye. Premaxillary with four broad, tricuspid teeth in the outer row, and five 
3- to 5-pointed teeth in the inner row. Maxillary with two or three conical 
or tricuspid teeth. Dentary with a series of four large, 5-pointed teeth followed 
by seven to ten small, conical or notched ones on the sides. 
Gill-rakers about 6 + 11. 
Anal sheath short, of about 5 seales covering the bases of the first 8 anal 
rays. Lateral line with pores developed on the first 10 or 11 scales. 
Origin of the dorsal equidistant from the snout and caudal, the penulti- 
mate ray two fifths of the longest, which is 3 in the length. Origin of the anal 
on the vertical from the last dorsal ray. Anal faleate, the longest ray almost 
equal to the base. Ventrals on the vertical from the first scale in front of the 
dorsal. Ventrals reaching to the third anal ray. Pectorals reaching the second 
scale beyond the base of the ventrals. 
Humeral spot small, semicircular, the curved margin directed upwards 
always very faint and often lacking. No caudal spot. Lateral stripe a nar- 
row, dark line overlaid with silvery. All the fins hyaline. A few chromato- 
phores at the base of each anal ray. Sides below the lateral stripe faintly 
iridescent. 
Two specimens, 45 and 48 mm. Rio Boa Ventura, (2943 c. m.) differ from 
the typical specimens of H. lunatus as follows:— the maxillary with two or 
three broad, 3-, 5- and 7-pointed teeth. Humeral spot very diffuse, lateral 
stripe not overlaid with silvery. 
21. HrMIGRAMMUS MICROSTOMUS Durbin. 
Hemigrammus microstomus DurBin MS. E1cenMann, Rept. Princeton univ. exped. Patagonia, 1910, 3, 
p. 436 (Amazon); Exiis, Ann. Carnegie mus., 1911, 8, p. 163 (Santarem). 
Hasrrat.— Amazon. 
Specimens examined. 
Number of Size 
Catalogue number specimens inmm. Locality Collector 
20782 Type 1 28 Santarem Bourget 
ie \ Paratypes 19 23-30 Santarem Bourget 
20840 Paratypes 5 30-37 Obidos James 
20970 1 34 Cudajas Thayer, Bourget 
2944 C. 7 29-34 Santarem Haseman 
