THE AMERICAN TETRAGONOPTERINAE. 169 
mouth is open. Maxillary 1.33 in the eye, much arched in front. Mandible 
longer than eye, 2.25 in head. Premaxillary with five to seven narrow, tri- 
cuspid teeth in the inner row, and two to three conical teeth in the outer row. 
Maxillary with three to five conical and tricuspid teeth. Dentary with a 
graduated series of five to seven tricuspid teeth, grading into a series of several 
minute conical teeth on the side. 
Gil-rakers 6 + 10. 
Anal sheath of 2 or 3 scales covering the bases of the first 7 to 9 anal rays. 
Lateral line with pores on 8 to 10 scales. 
Origin of the dorsal equidistant between snout and caudal, penultimate 
ray one third of longest which is 3.75 in the length. Origin of anal on the verti- 
cal from the second scale behind the dorsal. Anal emarginate, longest ray a 
little longer than the base. Caudal the length of the eye longer than the head, 
slightly less than the basal half scaled. Ventrals on the vertical from the origin 
of the dorsal. Ventrals barely reaching the anal, pectorals not usually reach- 
ing the ventrals in specimens over 43 mm. long. 
A faint, vertically elongate humeral spot, a slender black lateral stripe 
not reaching the caudal but overlaid with a silvery iridescent stripe which 
does extend to the caudal. The outer and sometimes the extreme tips of middle 
caudal rays slightly pigmented. The scales of the back and bases of the anal 
rays faintly outlined with brownish. A few chromatophores scattered over 
the dorsal and first anal rays. Iridescence on scales below the lateral stripe 
shading from rich copper on caudal peduncle to pale bluish on the lower series. 
No caudal spot. 
24. HrMIGRAMMUS CYLINDRICUS Durbin. 
Plate 22, fig. 5. 
Hemigrammus cylindricus Dursin, Ann. Carnegie mus., 1909, 6, p. 62 (Tumatumari); ErgenMAnn, Rept. 
Princeton univ. exped. Patagonia, 1910, 3, p. 426; Mem. Carnegie mus., 1912, 5, p. 337, pl. 49, fig. 3. 
Hasirat.— British Guiana. 
Specimens examined. 
Number of 
Catalogue number specimens Size in mm. Locality Collector 
1461 C. Type 1 57 Tumatumari Eigenmann 
1462 C., 11915 I. 6 35-58 Tumatumari Eigenmann 
Paratypes 
1163 C., 11916 I. 11 46-54 Crab Falls Eigenmann 
Paratypes 
