1920.] N. ANNANDALE & S. Ll. Hora: The Fish of Seistan. 187 
Adiposia macmahoni (Chaudhuri). 
(Plate XV. fie-t4 5 Plate XVIE fies. r & 22) 
1909. Nemachilus macmahoni, Chaudhuri, Rec. Ind. Mus., III, p. 341. 
As Dr, Chaudhuri’s description was based ona single speci- 
men not in the best condition and bleached by exposure to light, 
we give a fuller account of the 
species here, based on numer- 
ous well-preserved examples. 
The fish is one of the largest 
of its family, attaining a length 
of over 27 cm. and has an ex- 
tremely Siluroid appearance 
owing to its elongate form, 
broad, flattened head, and 
small, dorsal eyes. The dorsal 
profile immediately behind the 
head is somewhat convex, but 
both the dorsal and ventral 
profiles behind the dorsal fin)  Trxr-rre. 12.—Lower surface of head 
are neatly straight and parallel of Adiposta macmahont (X ?). 
and the greatest depth is con- 
tained 62 to a little over 8 times in the total length without the 
caudal, 74 to nearly Io times with the caudal. The head is 
depressed considerably below the profile of the back and its upper 
surface slants downwards from behind almost in a straight line ; 
it is broad and flat and its length is contained from 4% to 5 
times in the total length without the caudal. The specimens 
in our series seem to fall into two groups, in one of which 
the head is less flat and narrower than in the other. Possibly 
the difference is sexual, for it seems to be correlated with 
slight differences in the form of the vent, but the sexual 
organs are quite undeveloped in the fish recently collected, 
while they have been removed from the type. The length of the 
eye is contained 52 to 82 times in that of the head, but is rela- 
tively much less in the adult than in the young. ‘The pupil is 
nearly in the midddle of the head. ‘The nostrils are nearer to the 
eye than to the tip of the snout. ‘The barbels are subequal in 
length, which varies considerably ; the two anterior pairs usually 
reach to a vertical line from the nostrils if pressed backwards, and 
the posterior pair to one from the anterior border or middle of the 
eye. The cleft of the mouth does not reach as far back as the 
front of the eye. The anterior lip is continuous and minutely 
tubercular, the posterior lip smooth and widely interrupted in the 
middle line. The branchial isthmus is short and narrow. The 
chest and abdomen are flat. The pectoral fin, which is rounded 
at the tip, is much shorter than the head. The dorsal in quite 
young fish is higher than the body, but in the adult lower ; it is 
situated nearer the tip of the snout than the base of the caudal. 
The ventral and anal are short, the caudal of moderate length, 
