012 D. UM. S. Watson—Chelonian from the Purbeck, Swanage. 
The marginals of the right side of L. 9520 are preserved, although 
they are somewhat damaged. The fourth, fifth, and sixth have a 
rounded border; from the seventh to the tenth the edge becomes more 
and more acute, a change which may be accentuated by the crushing 
the specimen has undergone. The evidence points strongly to their 
having been eleven marginals; this is, however, not quite certain 
owing to the damage L. 9520 sustained at the hands of the quarry- 
man who found it. 
The whole surface is enamel-like and polished, the ornament 
consisting of irregular depressions and ridges; the sutures between 
bones are crossed by fine striz at right angles to their direction. 
Fic. 1. Restored dorsal view of the carapace of Glyptops ruetimeyert (Lyd.). 
The bones represented by full lines are present in one or other of the Manchester 
specimens. ‘The whole carapace within the peripherals is an accurate drawing 
of L. 7017; the peripherals are added from L. 9520, which is of precisely the 
same size as L. 7017. The contour of the two anterior peripherals is taken 
from Lydekker’s figure of the type-specimen. I have inserted in the figure all 
the sulci separating epidermal shields which I have been able to make out on 
both the Manchester specimens. { nat. size. 
Plastron.—The plastron is preserved in its natural position in 
L. 9520; it is flat, and very strongly resembles that of Pleurosternum. 
The anterior end is imperfect, the bridge is long, and the free posterior 
end narrows until the posterior border ends in a distinct notch. 
There are large mesoplastra, which meet in the middle line without 
appreciably narrowing. The entoplastron was probably rather longer 
than wide; qnly a fragment of the left epiplastron remains. The 
plastron is connected with the carapace by suture of the hyo-, meso-, 
nT 
