ae 
a new Chelonian. 147 
small and four-sided, the next six were hexagonal in outline, 
the antero-lateral border being very short; these six neurals 
(2-7) decrease in length from before backwards. The form 
and relations of the last neural are obscured by fractures, anc 
it cannot be seen whether it met the upper suprapygal or not. 
This latter is nearly triangular in outline, with rounded 
postero-lateral angles ; it is about as wide as it is long. The 
lower suprapygal is much wider than long, and its anterior 
border is longer than the posterior, which unites with the 
rectangular pygal. 
The anterior costal plate is comparatively large ; its poste- 
rior border is about 103 mm. long, and externally it meets 
the first and second marginals. ‘The second and third costals 
widen somewhat towards their outer end. The fourth costal 
is the longest (147 mm.), about three and a half times its 
width. The next four costals shorten successively, and all 
widen toward their outer ends. 
The marginals are large and take a considerable share in 
the formation of the carapace, especially in the hinder region, 
where in the case of the eighth and ninth their width (55 mm.) 
is greater than their length (45 mm.) measured along the 
edge of the shell ; in this region they are about twice as wide 
as the marginal shields. Marginals 2-8 form the support 
of the plastral bridge ; in 4, 5, and 6 the ventral portion of 
the bone makes an angle of a little less than a right angle 
with the dorsal portion, so that the edge of the shell in this 
region was very blunt; behind this the angle becomes more 
acute, till behind the bridge the carapace has a sharp edge. 
The sternal chambers must have been large. 
The rib of the first costal is well developed, and at the 
outer end of the plate there is a strongly developed facet for 
union with the upward prolongation of the hyoplastral bone 
forming the anterior buttress. The facet for the posterior 
(hyposternal) buttress is borne mainly by the fifth costal, but 
in part also by the sixth costal and eighth marginal. The 
eighth costal bears a roughened prominence, evidently for 
union with the upper end of the ilium. 
The nuchal epidermal shield was small, being very narrow 
from before backwards, ‘lhere were twelve pairs of marginal 
shields, much narrower than the marginal bones, with which 
they alternate. The anterior vertebral shield is about 108 mm. 
wide by 33 mm. long. The next three vertebral shields are 
rather wider, and their length is about two-thirds of the 
width. The last is nearly semicircular in outline. The form 
of the costal shields and their relations to the surrounding 
elements will be best understood from the figure. All the 
. he 
