ox THR AX ATOMY OP FISHES. 
221 
cseeal appendage. The walls of the bladder are extremely thin. The primary 
transverse septum is so obliquely placed that, while its lateral portions are vertical 
and directly-continuous with the ventral wall of the bladder, the median part is 
inclined downwards and forwards, and does not finally blend with the ventral wall 
until it almost reaches the inferior margin of the anterior wall. Through the 
obhquity of the septum, the lateral compartments and the longitudinal septum 
separating them are prolonged beneath the median portion of the anterior chamber 
nearly as far forwards as the anterior wall of the latter. The structure and skeletal 
attachments of the anterior chamber are otherwise perfectly normal. The inner half 
of each lateral compartment is subdivided by numerous secondary transverse septa, 
and these, with the root-like bundles which they give oflP dorsally and ventrally, 
largely obliterate the cavity of this part of the bladder. The outer portions of the 
compartments, on the contrary, are comparatively open and freely communicate in 
front with the cavity of the anterior chamber. 
The Weberian ossicles resemble those of other species of Pangasius, except that 
the inner extremity of the crescentic process of the tripus is not prolonged forwards 
towards the radial nodule in the form of a pointed projection. 
Pangasius juaro. 
This species substantially agrees with P. macronema in almost every respect. The 
flexible root of each “ elastic-spring” apparatus (fig. 95, t.pM.) is, however, even more 
slender, and the oval plate in which it terminates exceptionally large and extremely 
thin. In our solitary specimen there was no posterior csecum in connection with the 
normally subdivided portion of the bladder, but, as the Fish had been eviscerated 
before it came into our possession, it is possible that the csecum had been removed 
with the stomach and intestines. From the appearance of the posterior extremity of 
the bladder we incline to the opinion that a posterior csecal appendage does normally 
exist in this as in other species of Pangasius in which the “ elastic-spring” mechanism 
is present. In the relative proportions of the anterior and lateral compartments, and 
in the growth of a trabecular network of branching bundles of fibres in the latter, 
P. juaro closely resembles P. macronema. 
Silondia gangetica. 
Our solitary example of this species was a very young specimen about seven inches 
in length, and was one of the Indian Siluroids given to us by Dr. Day. The air- 
bladder has been briefly described by Taylor (38) as being very small in proportion 
to the bulk of the Fish. It is said to lie close to the anterior vertebrae, to be oval in 
shape, and divided internally into two cavities, each of which, in a Fish welgliing 
eight pounds, was not larger than a hazel nut. There is also a brief reference to the 
