1920.] N. ANNANDALE & S. L. Hora: The Fish of Seistan. 183 
slender, tubular diverticulum, which is directed back- 
wards from the transverse tube and ends in a vesicle. 
Type-species: Nemachilus macmahoni, Chaudhuri. 
Three species are known definitely to belong to this genus 
namely Nemachilus longicauda, Kessler,! N. rhadinaeus, Regan ® 
and N. macmahoni, Chaudhuti,? but the most important generic 
character (the adipose fin), which is by no means conspicuous in 
badly preserved specimens, has escaped the notice of most 
ichthyologists. Chaudhuri in his description of A. macmahoni 
refers to it as a fold of skin, but sections show that it is a structure 
of much more definite nature. We give a full description of it 
below. 
TEXT-FIG. 10.—Type specimens of Seistan species of Adiposia (reduced). 
a. A. rhadinaea (Regan). 
b. A. macmahoni (Chaudhuri). 
Two of the three species at present known are from Seistan, 
the third (A. longicauda) from Turkestan. 
The soft dorsal fin of Adiposta. ‘This fin has the form of a ridge 
arising a short distance behind the dorsal and extending to the base 
of the caudal, in which it finally disappears. The anterior margin 
slopes upwards and backwards gradually, the posterior extremity 
is ill-defined. Its reiative height varies in different species, and 
even to some extent in different individuals of the same species. 
In A. macmahoni the height may be as much as 2 of that of the 
caudal peduncle in well-preserved specimens, but in shrivelled 
! Kessler, ‘‘ Pisces’’ in Fedtschenko’s ‘‘ Reise in Turkestan,’’ p. 38, pl. vi, 
figss 22, 295(1374): 
2 Regan, Fourn. As. Soc. Bengal, II, p. 8 (1906). 
® Chaudhuri, Rec. 7nd. Mis., VII, p. 341 (1909). 
