36 
FOSSIL REPTILIA OF THE 
the character of the one described ; but some, at the base of the neck, have the central 
rising rough, and with a small pit in the middle. The same character is continued 
throughout the dorsal series, and the concavity is exaggerated in the vertebrae of the 
tail, which are, however, more concave than the others in all 'Plesiosauri. 
rt. la. 
The total length of the specimen preserved is . . . . .10 6 
The length of the cervical region preserved is ...... 4 0 
Fi'om the fore part of the coracoid to the hind part of the ischium . .36 
From the ischium to the end of the tail as far as preserved . . . .33 
The transverse breadth of the pubic bones across their broadest part is . . 1 If 
The fore-and-aft diameter of pubis at its middle part is . . . . 0 
Scapular arch and appendages (Tab. XIV). 
The humerus (Tab. XIV, 53) is 10 inches long, inches across its middle nar- 
rowest part, and 4| inches across its distal broadest part. The outer part of the head 
is somewhat produced, with a slight longitudinal depression on each side ; its surface 
is tuberous and rough; there is a low tuberosity on the hind part of the humerus, 
below its head. The contour of the anterior border of the bone is nearly straight, 
slightly wavy, first concave, then convex, again concave and more convex as it is 
rounded off to the lower border. The posterior margin is more deeply concave from 
the upper tuberosity to the posterior angle, which is rounded olf. The distal margin, 
convex in a general way, has its two surfaces sufficiently defined for the radius and 
ulna ; they do not, however, meet at so well-defined an angle as in some species ; a 
space of about an inch intervenes here between the radius and ulna in both right and 
left limbs, whereas they meet and touch each other in the PI. dolichodeirus (fig. 5) and 
PL Hawkinsii (fig. 6). The shaft of the humerus shows a tolerably smooth and longi- 
tudinally fibrous surface, but has a rough tuberculate character for about an inch and 
a half from the distal articulations. 
The radius (Tab. XIV, figs. 1 and 2, 54 ), 4 inches in length, is 2 inches 9 lines 
across the proximal end, 1 inch 10 lines across the distal end, 1 inch 6 lines across 
the middle. The radial or anterior margin is produced and somewhat thickened 
below the head, making the margin beyond it concave half way towards the distal end ; 
the posterior or ulnar border is uniformly and moderately concave ; the distal border 
of the radius is straight from its ulnar angle to near its radial one, where it becomes 
convex, that angle being, as it were, cut off. This distal border is most closely articu- 
lated, seems, indeed, partially confluent, with the scaphoid. The ulna (Tab. XIV, figs. 
I and 2, 55 ) would present its usual reniform shape, were it not that the proximal angle 
of the posterior or ulnar border is produced into a sort of olecranon (fig. 2, 55'). This 
process is separated by a fissure or fracture from the body of the bone ; but as this 
