ON THE ANATOMY OF FISHES. 
‘201 
layer of fatty tissue is interposed between the outer walls of the anterior chamber and 
the lateral cutaneous areas. 
The Weberian ossicles are also very similar to those of Plotosus, but the crescentic 
process of the trlpus, like that of Cnidoglanis is strongly decurved towards its hinder 
or inner extremity and closely applied to the lateral surface of the complex centrum. 
Silurus cochinchinensis. 
Day (9) thus refers to the air-bladder of this species : “Air vessel in the abdominal 
cavity not enclosed in bone.” In all probability the organ is perfectly normal and 
resembles that of S. glanis. 
Wallago attu. 
There is no essential difference between this Siluroid and Plotosus canius or 
Silurus glanis in the structure of the air-bladder or in the character of the skeletal 
modification.* 
The anterior division of each of the transverse processes of the fourth vertebra is 
strongly decurved in relation with the antero-lateral region of the air-bladder as in 
Macrones, but without being prolonged into a crescentic process. Near the distal 
end of the process there is an elongated concave facet for articulation anteriorly with 
the post-temporal. There are no subvertebral processes. 
In proportion to its width the air-bladder is rather long and somewhat compressed, 
so that its depth is equal to, if not greater than, its width. The anterior chamber is 
relatively small, but on the other hand the lateral compartments are very large and 
extend backwards in the abdominal cavity as far as the transverse processes and 
ribs of the thirteenth or fourteenth vertebra. The primary transverse septum is a 
stout, vertical pillar produced into two ridges anteriorly as in Arius, which combine 
to form a single inwardly projecting ridge along the inner surface of the ventral wall 
of the anterior chamber, and eventually along the median portion of the anterior wall. 
The longitudinal septum is a tympaniform sheet of fibres somewhat thinner than the 
remaining walls of the lateral compartments. 
The Weberian ossicles closely resemble those of Cnidoglanis megastoma. 
Eutropiichthys vacha. 
We have only been able to examine a skeleton of this species (fig. 85), but as our 
description of the modifications which the anterior vertebrae and their processes 
* The air-bladder of Wallago has been referred to by Day (9) as follows : “ Air-vessel of moderate 
size, situated in the anterior part of the abdomen ; on removing its front wall it is found to bo divided 
into two lateral chambers by a longitudinal septum, which, however, has a round orifice anteriorly so 
as to admit of free communication between the two sides.” 
2 D 
MDCCCXCIir. — B, 
