ANNOTATED LIST OF THE SPECIES 317 
Dorsal sealation lacking; mouth large while that of Higenmannia is minute; 
unlike in that the jaws are more nearly equal; dorsal profile of the head concave 
(Higenmannia convex). 
No caudal fin or dorsal filament; snout not projecting; eye without a free 
margin; back naked to a point over the last third of the anal fin; mouth terminal, 
large, the maxillary very oblique; mandible rounded or pointed; mandibular teeth 
in four regular rows across the front, none on the lateral rami; teeth of the upper 
jaw in about five less regular series. 
441. RHABDOLICHOPS LONGICAUDATUS Eigenmann and Allen, sp. noy. 
Plate XVI, figs. 3 and 4 
15436, 1, 497 mm., total length, type, Iquitos, Morris, 1922. 
15810, 1, 840 mm., total length, paratype, Iquitos, Allen, September, 1920. 
15996, 3, 400-415 mm. to end of anal fin, paratypes, Iquitos, Morris, 1922. 
Of the five specimens one appears to be more nearly normally proportioned, 
and it is designated as the type. The others all have enormously exaggerated tails, 
which are tumid and greatly prolonged. It would seem impossible for such a 
species, even in a streamline-conscious era, to exist, carrying a tail of the dimensions 
of no. 15810, for instance; impossible for it to survive in waters teeming with 
rapacious fishes among which even conservative Gymnotids so frequently suffer 
mutilations. 
Description of the type: 
Head 14; depth 12; A. 254; length to the end of the anal fin 317 mm., tail 180 
mm.; snout 3.5 in the head; eye 6.36; interorbital 6; depth of head equal to half its 
length; anus under the vertical from the eye; origin of anal fin behind the vertical 
from the base of the pectoral fin; pectoral 0.7 in the length of the head; upper 
profile of the head depressed, the lower strongly convex; mouth large, terminal; 
gape slightly oblique when the mouth is closed, the maxillary nearly vertical when 
the mouth is open; free edge of the maxillary nearly equal to the snout. 
Scales of the lateral line large, those above and below it smaller; back naked, 
the naked area extending down to the lateral line at its origin, becoming more 
constricted caudally; about 130 scales in the lateral line forward from the end of 
the anal fin. 
Back dusky, sides light, no definite markings. 
As stated above, only the type seems to have a normal tail, unless we may con- 
sider the hypertrophy of the majority asa normal. Of the other four specimens the 
tail is unusual, if not indeed abnormal. In two of these the tail has been broken 
in life, and the ends are lost, either in the digestive tracts of fishes, or incidentally to 
the collecting procedure. Of the two remaining, one has a pointed tail 432 mm. 
long, of the usual shape. Without the appendage the specimen, 15810, is 408 mm. 
in length, that is, the tail exceeds the owner in length; the anal has 237 rays. In 
the fourth specimen the tail appears broken at a point about 210 mm. beyond the 
anal, and is continued as a bag about 40 mm. long, covered with thin scales. The 
end of the bag is blunt, suggesting a second injury. Total length of this specimen 
is 670 mm., 420 to the end of the anal fin, tail 250 mm. 
