212 
PROFESSORS T. W. BRIDGE AND A. C. HADDON 
fresh specimen, on the contrary, a ventral wall to each semi-cylinder is furnished by a 
tough fibrous membrane which stretches between, and is attached to, the decurved 
margins of the transverse process, and is also continued over the ventral surface of the 
air-bladder, while the distal apertures of the seini-cylinders are closed by the external 
skin. The transverse process of the fifth vertebra {t.p}) is a short flattened process 
of bone, free proximally but suturally united at its distal extremity to a small projec- 
tion from the deflected posterior margin of the preceding process. The transverse 
processes of the sixth vertebra carry the first pair of ribs. 
Superficial ossifications {s.os) considerably thicken the sides, and especially the 
ventro-lateral margins of the complex and fifth vertebral centra, and even overlap the 
body of the sixth vertebra behind, as well as obscure the centrum of the first vertebra 
and blend with the basioccipital in front. The ventral edges of the ossifications are 
not only thickened but flattened out laterally so as to give rise to two longitudinal 
ridges the free margins of which are directed outwards. These ridges are very similar 
to the ventral ridges of Bagarius, but, while they enclose between them a shallow 
aortic groove {(i.g.), do not give rise to even a trace of the ventral processes so 
characteristic of the last-mentioned Siluroid. There are no obvious grooves for the 
posterior cardinal veins, nor could we discover any trace of radial nodules or dorsal 
laminae. 
The post-temporal has a very slender inferior limb [p)t.i.) which is directed obliquely 
forwards to its articulation with the basi-occipital, and for the distal half of its length 
is closely applied to the anterior wall of the semi-cylindrical transverse process. The 
ascending process {pt., a.), is somewhat flattened, and has the usual articulation with 
the epiotic, pterotic, and supra-occipital bones of the skull. The stem of the post- 
temporal {pt., s.), is deeply cleft into a long outer and much shorter inner process, 
which enclose between them a socket for the head of the clavicle. The inner of the 
two processes is firmly applied to the anterior margin of the distal aperture of the 
bony semi-cylinder of the same side. 
In the skull the recesses for the sacculi are exceptionally small, but the cavum sinus 
imparis and the atrial cavities appeared to be perfectly normal. 
The air-bladder {a.h.) is broadly ovate in shape and greatly flattened.* Along its 
median antero-posterior axis the bladder is perfectly solid, owing apparently to the 
fusion of its dorsal and ventral walls anteriorly, and to the exceptional thickness of 
the longitudinal septum posteriorly, and is also moulded and closely adherent to the 
lateral and ventral surfaces of the complex and fifth vertebral centra, more especially 
to the flattened-out ventral margins of the superficial ossifications. Laterally to this 
longitudinal partition each half of the bladder is hollow and rests by its dorsal surface 
on the roots of the transverse processes of the fourth and fifth vertebras, and to some 
extent bulges outwards into the cavity of the corresponding'^bony semi-cylinder, but 
* In a specimen, eight inches long, the maximum width of the organ was 11 mm., and the length 
9'. 5 mm. 
