176 
PROFESSORS T. W. BRIDGE AND A. C. HADDON 
membrane, with skeletal attachments in every way similar to those of the corresponding 
structure in Auclienipterus, invests the proper anterior wall of the bladder. 
With reference to the mode of growth of the terminal plates of the “elastic- 
spring” apparatus, Sorensen says (37, p. 140); “Chez le genre Malapterurus, le 
disque mince du ressort n’est pas une ossification de la vessie natatoire (car on pent 
en suivre la membrane externe le long de sa surface post^rieure concave), mais 
seulement de la plevre, qui est tres 6paisse et tres ferme en avant, a cote de la partie 
anterieure de la vessie natatoire.” The plates are not, therefore, to be regarded as 
ossifications of any portion of the tunica externa, but of the transverse membrane only. 
The Weberian ossicles require no special description. The scaphlum has a long 
and slender ascending process, in addition to spatulate and condylar processes. The 
intercalariurn is a small nodule of bone in the interossicular ligament. The crescentic 
process of the tripus curves gradually downwards and inwards from its root towards, 
and in contact with, the lateral surface of the complex centrum. Claustra are 
present and occupy their usual position, one on either side of the foramen 
magnum. 
We could detect no deviation from the normal type, either in the structure of the 
membranous labyrinth of the internal ear, or in the structure and mode of formation 
of the cavum sinus imparis and atrial cavities. 
The dorso-lateral and ventro-lateral muscles of the trunk diverge so slightly that 
special lateral cutaneous areas can hardly be said to exist. 
Mala pterurus henineyisis. 
From Cleland’s account (Ga) it may be inferred that this species closely resembles 
M. electricus. except that the intercalariurn is said to be absent. 
Sub-Family SILURID^ ANOMALOPTERiE. 
Group : — Hypoptithalmina. 
Hypophthalmiis marginatus. 
Ramsay Wright (44) has given an account of the air-bladder and anterior 
vertebrae of this aberrant Siluroid. To admit of comparison with other types, a brief 
statement of his results may not be out of place, more particularly as Hypophtlialmus 
exhibits a remarkably abnormal condition of these structures, and is, moreover, one 
of the nine genera of Siluridm in which Johannes Muller denied the existence of 
an air-bladder. 
Complete anchylosis has taken place between the conjoined anterior vertebrae from 
the first to the fifth inclusive. These vertebrae apparently form a “ complex,” which 
represents not only the complex vertebrae of other Siluroids, but the first and fifth 
