4 
FOSSIL REPTILIA OE THE LONDON CLAY. 
in connection with the intervening neural plates, which are entire save some abrasion of 
the outer surface of the hinder ones and slight mutilation of the sutural borders. 
The costal plates, of which the proximal parts of four are preserved on the right side, 
have been slightly dislocated from their marginal sutures with the neural plates by super- 
incumbent pressure. A longitudinal extent of eight and a half inches is preserved of 
the left sixth costal plate. 
On the under part of the mass of petrified clay to which the above-described 
portion of carapace is cemented the expanded sternal portions of the pair of cora- 
coid bones are preserved converging to the median line ; a portion of the xiphoid 
production of the entosternum extends along the medial line in advance of the 
broad ends of the converging coracoids. This is the chief recognisable part of the 
plastron here preserved, but it adds to the testimony against the Sphargis affinity, in 
which genus the entosternal does not send backward such xiphoid process. 
The breadth of the sternal end of the coracoid of Chelone gigas is six inches ; that 
of the scapular end shown in another portion of the matrix is two inches and a half ; the 
total length of the coracoid is one foot five inches. 
