22 MARINE REPTILES OF THE OXFOED CLAT. 



E. 3536. A great part of the skeleton of a very large individual. The parts preserved are : — 

 skull, mandible, many teeth, atlas and axis (fused), and twenty other cervical vertebrae 

 (test-fig. 2) mostly wanting neural arches and ribs ; twenty-three centra of dorsal 

 vertebra? and fourteen caudals (text-fig. 3) ; numerous neural arches and cervical, dorsal, 

 and caudal ribs ; ventral ribs ; portions of coracoid and scapula, humerus, radius, ulna, 

 and numerous paddle-bones ; pubes and ischium (text-fig. 7). 



The skull in this specimen wants the roof between the external nares and the pineal 

 foramen ; the middle portion of the palate and the zygomatic arches are also wanting. 

 The presence of sclerotic plates (see page 9) in this specimen is of interest. No 

 teeth, except some of the uncut crowns of successional teeth, were found in situ. The 

 cervical vertebras are fairly well preserved, the neural arches and the cervical ribs in 

 all cases separate ; dorsals and caudals much crushed. The terminal caudals are 

 present, showing the very rapid diminution in the size of the centra at the end of the 

 tail. 



The shoulder-girdle is badly preserved, but the proximal part of one fore paddle is in 

 good condition. The humerus shows well that the distal expansion was a little more 

 marked than in Peloneustes, and that the whole bone was more slender than in Simo- 

 lestes. The enormous pubes and the ischium have been crushed out to nearly flat plates 

 of bone. 



The approximate dimensions (in centimetres) of this specimen are : — 



Skull : length from quadrate to tip of snout 154-0 



„ „ occipital condyle to tip of snout . . . 126-5 



transverse diameter of occipital condyle 8-0 



width between outer ends of quadrates 72-0 



width of quadrate 15-0 



width of snout at constriction 13-7 



,, ,, „ widest part of anterior expansion . 15-4 



Mandible : extreme length 154-0 



length of symphysis 30-5 



width just behind symphysis 17 - 



„ of articular surface 16-7 



length of postarticular process 10-5 



Teeth : 



Length along middle of curve .... 19-0 . . 7"8 



Height of crown 7-5 7'0 2-5 



Greatest diameter of base of crown . . 3-0 2-7 1'5 



Vertebra Atlas and 4th 15th 17th 23rd Anterior 



axis. (cervical), (cervical), (cervical), (pectoral). 



Length of centrum on mid-ventral line . 5-6 4-9 4-3 5-0 5-1 6-0 4-5 



Vi'idth of posterior face of centrum . . 10-0 12-0 llo 12-8 12-5 10-5 10-0 



Height of posterior face of centrum . . 8-9 10-4 10-6 11-0 11-5 8-6 9-1 



„ to top of neural spine 30-9 32-9 33-0 



„ of neural arch 22-2 21-7 



of neural spine . . 17-3 17-0 



