108 
PROFESSORS T. W. BRIDGE AND A. C. HADDON 
pointed distal extremity, but confluent at its broad base with the root of the preceding 
process [t.p. 5). 
Superficial ossifications greatly thicken the ventro-lateral margins of the complex 
and fiftli vertebral centra, and there form well-marked longitudinal ridges ; they are 
also produced ventrally and enclose between them a fairly conspicuous groove for the 
dorsal aorta (fig. 29, Ci.g.). Near the hinder extremity of the complex centrum each 
longitudinal ridge is produced slightly outwards into a short triangular process 
(fig. 29), which is clearly a rudimentary representative of the very similar, but much 
more pronounced ventral process of Bagarius and Glyptosternum, and, like the latter, 
has its origin from a ridge-like thickening of the superficial ossification. We could 
detect no trace of an oblique lateral ridge in connection with the complex centrum, 
but a dorsal lamina is on each side represented by a thin slender spicule of bone 
which becomes detached from the ventral surface of the modified transverse process 
at a point a little behind, and to the inner side of, the distant extremity of the 
crescentic process of the tripus, and, after passing downwards, inwards, and a little 
forwards, ventrad to the cardinal groove, terminates in a free extremity close to the 
lateral surface of the complex centrum, or rather is connected with the latter by a 
fibrous extension only (fig. 29, d.l.). The groove for the posterior cardinal vein is 
very evident on the right side, between the thickened ventro-lateral edges of the 
complex and fifth centra and the ventral surfaces of the roots of the contiguous 
transverse processes. In the region of the dorsal lamina, it is obvious that, as usual, 
the groove is almost completely encircled by bone. On the left side the groove is 
inconspicuous. 
The ascending process, and the stem of the post-temporal together form an 
expanded plate of bone at each of the postero-lateral angles of the skull, which covers 
the epiotic and articulates in the usual way with the pterotic in front, and the supra- 
occipital above. The inferior limb {'pt. i.) is very slender, and has but a slight 
forward inclination as it passes inwards to join the basioccipital (6.O.). Its outer 
extremity firmly articulates with the recurved distal end of the anterior division of 
the modified transverse process, and the two, in conjunction with the inner surface of 
the post-temporal stem, combine to form a deep articular groove for the proximal 
extremity of the clavicle {cl.). 
The air-bladder is represented by two laterally- situated and somewhat ovoid, 
thin- walled sacs, each of which occupies the concavity of the bony recess, formed by 
the modified transverse process of its side'"" (fig. 30, a.s.). There is no trace of lateral 
compartments, or of any connection between the two sacs otherwise than by a thin 
solid stratum of fibres, which extends transversely between the two, and in the 
median line is firmly adherent to the ventral surface of the complex centrum ; 
neither could we detect any trace of a ductus pneumaticus. The anterior and 
* Tn a specimen three and a half inches in length, each air-sac was 3'5 mm. long and 2‘7 mm. 
in width. 
