THE AMERICAN TETRAGONOPTERINAE. 149 
Specimens examined. 
Number of 
Catalogue number specimens Size in mm. Locality Collector 
20738 Type 1 47 Lago do Maximo Agassiz 
20738 Paratypes 201 35-48 Lago do Maximo Agassiz 
20838 Paratypes 18 33-45 Chidas James 
20829 Paratypes 3 38-44 Chidas James 
20716 Paratypes 63 34441 Villa Bella Agassiz 
20749 Paratypes 35 44-47 Lake Jose Assu Agassiz 
3088 C. 2 31, 38 Santarem Haseman 
Head 3.5 to 3.66; depth 3.2 to 3.6; D. 11; rarely 10; A. 17-20; scales 
5-30 to 34 to 3.5; eye 2.5 to 2.67 in the head; interorbitals slightly less than 
the eye. 
Compressed, head short, depth of head at the base of the occipital process 
1.5 in the greatest depth. Preventral region rounded, usually without com- 
plete series of median scales; sometimes a more or less regular series of 12 or 
13 scales, the last enlarged. Predorsal region rounded, a regular median series 
of 9 scales. 
Occipital process one sixth of the distance from its base to the origin of 
the dorsal. Bordered on the side by two or three scales. Interorbital slightly 
convex. Frontal fontanel narrowly triangular, just or a little less than equal 
to the parietal without the occipital groove. Second suborbital leaving a 
narrow naked margin behind and below it. Maxillary equal to the length 
of the eye. Mandible a little longer than the eye. Snout short, about 1.3 in 
the length of the eye; mouth large. Premaxillary with three, sometimes four, 
3-pointed teeth in the outer row, and five, the middle 6- to 7- and the rest 7- to 
9-pointed teeth in the inner row. Maxillary without teeth. Dentary with 
five large or four large and one small, 7- to 9-pointed teeth, several minute coni- 
eal teeth on the sides. 
Gill-rakers 8 + 12. 
Anal sheath short, consisting of 2 or 3 scales covering the bases of the 
first 6 or 7 rays. Lateral line developed on from 6 to 11 scales. 
Origin of the dorsal equidistant from snout and caudal. Penultimate 
ray 2.33 in the longest which is 3.67 to 4 in the length. Caudal equal to the 
length of the head. 
Origin of the anal on the vertical from the first or second scale behind the 
dorsal. Ventrals on the vertical from the origin of the dorsal. Pectorals not 
reaching the ventrals; ventrals almost reaching the anal. 
