1920.] N. ANNANDALE & S. L. Hora: The Fish of Setstan. 185 
have not been able to examine specimens of this genus preserved 
for histological investigation, but we have cut sections of the 
fin in a species of the related genus Glyptosternum. We have also 
sectioned the primitive dorsal fold in post-larval specimens of a 
species of Nemachilus. Before discussing the significance of the 
structure in Adiposia, we must give a brief account of that found 
in these other fish. 
In young specimens of Nemachilus evezardi recently ob- 
tained by Major R. B. Seymour Sewell at Khandalla and easily 
recognized by the presence of a nasal barbel', the primitive dorsal 
fin-fold remains in a very interesting condition until the fish is 
at least 1 cm. long. The dorsal fin of the adult is already well- 
developed and has its rays fully formed, but behind it the fold 
persists, extending into the caudal. The anterior extremity of 
this vestige of the fold slopes gradually upwards and backwards. 
Externally the whole structure has a very close resemblance to the 
same parts of Adiposia. Indeed, the only differences to be noted 
TExT-FiG. 11.—Young of Nemachtlus evezardi 1 cm. long showing 
dorsal fold. 
on a superficial examination are that the ceratotrichia are well 
developed, especially in the posterior part of the fold, and that 
the fold also extends forwards from the caudal on the ventral 
surface. 
We have examined a large number of species of Nemachilus 
from both mountainous regions and comparatively level country 
for traces of the persistence of this condition. In all we finda 
short, compressed pad, clearly representing the posterior part of 
the fold, at the base of the caudal fin both above and below. 
In some this fold persists as a ridge to a comparatively late 
age. In N. savona it is in this condition in a specimen 39 mm. 
long. 
In vertical sections of the dorsal fold in a young N. evezardi 
about I cm. long we find the structure essentially similar to that 
of the soft fin of Adiposta, but, as might be expected, the tissues 
are less differentiated. The outer wall is thinner, its gland-cells 
are more numerous and its epithelial cells less distinct. The layer 
L Jordan and Fowler regard this as a generic character but we are not pre- 
pared to accept their view. 
