106 
PROFESSOKS T. W. BRIDGE AND A. C. HADDON 
agree in the extent of their growth with those of Macrones nemurus. The oblique 
lateral ridges of the complex centrum are but feebly developed, and each ridge is 
directly continuous with the dorsal lamina of its side. The radial nodule is a short 
but thick ossification, firmly attached, but not anchylosed, to about the centre of the 
confluent lateral ridge and dorsal lamina. The stem and ascending process of the 
post-temporal together form a broad granulated plate which is freely exposed on the 
siu’face of the body, near the postero-lateral angle of the skull. The posterior process 
of the clavicle (fig. 27, cl.p.) is unusually long and broad, and extends backwards to 
about the level of the second rib ; its upper margin is slightly concave, and coincides 
with the inferior limit of the lateral cutaneous areas of its side. 
The anterior chamber of the air-bladder (fig. 27, ax.) has the normal size relatively 
to that of the body, but the lateral compartments {l.c.) are very imperfectly developed, 
although they have the usual relations to the former, and are separated from each other 
by a short, stout, longitudinal septum {l.s.). The primary transverse septum {t.s.) is some- 
what contracted but extremely thick, and its dorsal edge has an extensive attachment 
to the lateral surfaces of the centrum of the fifth vertebra and to the ventral surfaces of 
its transverse processes. The anterior wall of the bladder is firmly buttressed by the 
anterior divisions of the modified transverse processes {t.p.^a.), and externally to this, 
in the antero-lateral regions, by the concave inner surfaces of the clavicle and its 
posterior process. Apparently by way of compensation for the small size of the 
lateral chambers, two comparatively thin-walled cmcal diverticula are given off from 
the postero-lateral regions of the anterior chamber, which extend backwards, one on 
each side of the abdominal cavity nearly as far as the anus (fig. 27, c.dv.). These 
diverticula are simple cmca, tubular in shape, and of fairly uniform calibre through- 
out, but communicating with the anterior chamber by wide funnel-shaped mouths, 
situated at the outer side of the apertures whereby the same compartment opens into 
the two rudimentary lateral chambers. The cavities of tlie caeca are simple and 
undivided. In a brief reference to the air-bladder of this species. Day (9) describes 
the right caecal diverticulum as usually passing over to the left side, and then curving 
across the commencement of the left one, while the latter at first passes backwards 
and is then sometimes curved on itself, but in the only specimen at our disposal the 
caeca pursued a fairly straight course backwards towards the anus, and finally bent 
slightly inwards towards each other. With the exception of these caecal outgrowths 
the walls of the air-bladder are exceptionally thick, but nevertheless retain their 
normal attachments both to fixed portions of the skeleton and to the moveable 
tripodes. It will be noticed, however, that the dorsal attachments of the lateral 
portions of the primary transverse septum are to the ventral surfaces of the transverse 
processes of the fifth vertebra, instead of, as in Macrones, to those of the fourth 
vertebra, and it is apparently due to the backward shifting of these attachments that 
the posterior pillars lose their direct insertion into the posterior margins of the dorsal 
laminae. 
