202 
PROFESSORS T. W. BRIDGE AND A. C. HADDON 
undergo in SchUhichthys rjarua (p. 211, lig. 89) will apply with scarcely any altera- 
tion to the former, it may perhaps be concluded that we have here a somewhat 
similar example of a vestigial and degenerate type of air-bladder. Day (9), in 
his paper on the ‘ Freshwater Siluroids of India,’ briefly refers to the air-bladder 
of Eutropiiclilhys in the following terms : “ Air-vessel narrow, tubiform, placed trans- 
versely across the body of the anterior vertebra, and all but its central portion 
enclosed in bone, either expanded extremity being within a bony capsule ” {loc. cit., 
p. 713). This description does not give suflScient details to admit of comparison 
with other types, but taken in conjunction with the characteristic modifications of the 
anterior transverse processes it supports the conclusion suggested above. 
Cryptopterus micronema. 
With the exception of the two abnormal species, C. micropits and C. hexapferus, the 
skeletal modifications in the remaining species of the genus that we examined are 
almost identical with those of Callichrous ceylonensis* Perhaps the most striking 
feature in the different species of Cryptopterus is the marked elongation of the caudal 
at the expense of the abdominal region of the body, which is also accompanied by 
a corresponding reduction in the number of vertebrae carrying free ribs to three or 
four, viz., the fifth or sixth to the seventh or eighth, inclusive. The effect of this on 
the air-bladder is two-fold, and either leads to the backward extension of the organ 
into the lateral musculature of the tail, or to the assumption of a shortened and 
almost globose shape. 
The large air-bladder of C. micronema is on the whole very similar to that of 
Callichrous, except that the anterior chamber is relatively small and faintly bilobed 
in front, while the lateral compartments gradually contract into a long, tapering, 
tubular prolongation which, after traversing the short abdomen, extends into the 
anterior third of the tail, and there lies on the right side of, and in contact with, the 
haemal arches, internal to the lateral caudal muscles. The longitudinal septum is also 
prolonged backwards into this singular caecal extension, and sub-divides its cavity 
into two lateral canals which, anteriorly, communicate with their respective lateral 
compartments. The walls of the bladder are very thin, and on each side, for a limited 
extent, the anterior chamber is in contact with a hlister-like lateral cutaneous area, 
but this region of the body is not specially translucent.! 
The Weberian ossicles, also, are very similar to those of Callichrous; the inter- 
calarium has a horizontal process, but no trace of an ascending portion. 
* See p. 20G. 
t In tliis and in all the remaining species of Cryptopterus, the disposition and skeletal attachments of 
the fibres foi’ming the walls of the anterior chamber are almost precisely the same as in Mnerones 
nemurus. 
