ON THE ANATOMY OP FISHES. 
195 
intercalariuin, and the interossicular ligament was so short that the anterior 
extremity of the tripus appeared to be almost in direct contact with the outer surface 
of the spatulate process of the scaphium. The latter ossicle has the usual spatulate 
and condylar processes, but no ascending process. We could find no trace of claustra. 
As far as the grosser features in the structure of the auditory organ are concerned 
we could detect no indication of retrogressive modification. A transverse ductus 
endolymphaticus and a sinus endolymphaticus are present, and the latter structure 
has the usual relations to the cavum sinus imparis and the atrial cavities. The 
closure of the external atrial aperture is effected in the usual manner by the spatulate 
process of the scaphium. 
Clarias magur, C. fuscus, and C. anguillaris. 
These species very closely resemble C. nieuhojii in all essential features, and, there- 
fore, require no special description. There is, however, in each species, a fully 
developed, nodular iutercalarium in the interossicular ligament. 
(Jlarias macr acanthus. 
The anterior vertebrae and bony capsules of this species have been figured and 
briefly described by Sokensen (37, figs. 29, 30), but no special reference is made to the 
air-bladder, or auditory organ. The Weberian ossicles are also figured (Zoc. cit., figs. 
316, 3l6), including a small iutercalarium in the interossicular ligament. 
Heterohranchus (sp ?). 
We have had no opportunity of examining a species of this genus, but as the 
structure of the dorsal fin is almost the only point of importance in which Hetero- 
hranchus differs from Clarias, it is probable that the air-bladder and Weberian 
ossicles are much the same in the two genera. The only reference that we have been 
able to discover is by Johannes Muller (28), whose brief description of the air- 
bladder of Heterohranchus, as being enclosed in bone, to some extent confirms our 
suggestion that it will be found to resemble that of Clarias, 
Group : — Plotosina. 
Plotosus canius. 
In Plotosus we again meet with an air-bladder of the normal type and with skeletal 
modifications of a very simple character. 
The body of the first vertebra (fig. 82, v.^) is free and distinct but small. The 
complex and fifth vertebrae (c.c., v.^) are about equal in size and firmly connected 
2 c 2 
