THE AMERICAN TETRAGONOPTERINAE. 151 
rather narrow. Caudal equal to the head. Ventral on the vertical from the 
first dorsal ray. Ventrals not quite reaching to the anal. Pectoral reaching 
to within one scale of the ventrals. 
Fins all a little dusky, without definite markings. No humeral spot. A 
narrow black lateral stripe, faint from the head to the vertical from the origin 
of the anal and ending abruptly before it meets the caudal spot, which is con- 
tinued to the end of the middle caudal rays. Scales of the back with rather 
broad dark margins. 
10. HrmMIGRAMMUS HYANUARY Durbin. 
Plate 18, fig. 4. 
Hemigrammus hyanuary Durpin Ms. Etcenmann, Rept. Princeton univ. exped. Patagonia, 1910, 3, 
p. 436. 
Eight specimens 20955 40-44 mm. Lake Hyanuary Navez 
Head 3.5-4; depth 3.6-3.8; D.11; A. 14-15; scales 5-32 or 33-3; eye 
2.67 in head, snout 1.5 in the eye; interorbital almost equal to the eye, very 
nearly 2.75 in the head. 
Compressed, depth of head at base of occipital process 1.25 to 1.33 in the 
greatest depth. Preventral region rounded without complete series of median 
scales. Predorsal region rounded with regular median series of about 9 scales. 
Occipital process about 8 in the distance from its base to the dorsal, bor- 
dered by 2 and 1.5 scales. Interorbital almost flat. Frontal fontanel much 
narrower than the parietal, equilaterally triangular, very small about one 
fourth the parietal without the occipital groove. Second suborbital leaving 
a narrow naked margin behind and below. Snout short but not so short as 
in H. matei; mouth large. Lower jaw included only when the mouth is closed. 
Maxillary 1.25 in the eye. Mandible about equal to the eye, 2.75 in the head. 
Premaxillary with four, narrow, tricuspid teeth in the outer row, and five, rarely 
six, large 3- to 5-pointed teeth in the inner row. Maxillary with one or two 
narrow 4-pointed teeth. Dentary with four or five large 4- to 6-pointed teeth 
in a graduated series followed by five or six minute teeth on the sides. 
Gill-rakers 6 + 8. 
Lateral line with pores developed on 8 to 10 scales. 
Origin of the dorsal less than the length of the eye nearer the snout than 
the caudal; penultimate ray one third of the longest which is 3.75 in the length. 
Origin of the anal on the vertical from the second scale behind the dorsal. Anal 
