146 MAEINE EEPTILES OF THE OXFOED CLAT. 



numerous separate cervical and caudal ribs, ? chevrons, radius and ulna^ femora, 

 tibia, and fibula. 



The dimensions (in centimetres) o£ this specimen are : — 



Skull : 



Length of basioccipital 2-3 



Width of quadrate articulation 1'4 



Mandible (PL Vn. fig. 1): 



Width of articular surface for quadrate I'i 



Length of postarticular region (least) 2-1 



Length from angle to hinder end of dental series .... 7-2 



Cervicals. 



Vf>rtebro2 "I Atlas and , • * ^ 



(PI. YII. figs. 5, 5 a, 5 6, 6) J axis. Srd. 10th. 15th. 20th. 25th. SOth. 35th. 



Length of centrum in 



mid-yentral line . . 27 1-6 2-1 2 6 2-9 31 3-1 3-1 



"Width of posterior face . 2-0 2-0 2-5 2-9 3-3 3-7 4-1 4-3 



Height of posterior 



face 1-3 1-3 1-G 2-0 2-4 2'5 27 2-7(app.) 



Height to top of neural 



spiue 3-2 .. 4-0+ 6-0(app.) 6-2(app.) 8-5 



Caudals. 



r— : ^ ^ ^ 



Anterior. Anterior*. Behind last. t urtiier back. 



Length in mid-ventral line . 2-3 2-2 2-3 2-0 1-8 1-5 



Width of posterior face . . 36 37 3-2 2-6 2-5 2-0 



Height of posterior face . . 2-4 2-3 2-5 2-1 1-9 1-6 



Height to top of neural spine . . 6'5 6-8 4'6 4-6 



Eadius : length of outer border 6-6 



„ inner border 3'8 



width of proximal end 5'1 



„ distal end 4*9 



Ulna : greatest length 5-2 



„ width 5-2 



Femur: length 16-0 



diameter of head (approx.) 3'8 



greatest width of proximal end 5'2 



width of shaft at narrowest 3-.5 



,, distal expansion 8'6 



Picrocleidus sj). 



In addition to the skeletons undoubtedly belonging to the type species of this 

 genus, there are remains of a small Plesiosaur which is probably referable to this 

 genus, but differs from the typical form in the shape of the centra of the cervical 



* First with facets for chevrons. 



