70 MARINE EEPTILES OF THE OXEOED CLAY. 



Supraoccipital : extreme width ''5 



„ height 4-9 



width of neural opening at lower end ... 1'2 

 width between inner edges of the foramina 



marked {for.) in test-figure 2, C, D . . . 5-9 



Stapes : greatest length 7'6 



,, thickness of inner end 5'2 



Opisthotic : greatest length 7-8 



„ width of inner end 4-7 



Quadrate : greatest length 12-3 



„ width of articular surface . . (approx.) 4-5 



Basisphenoid : greatest length 7'5 



width 11-0 



Parietal : total length in straight line 17'2 



greatest width 6'5 



R. 2161 (Leeds Coll. 90). Bones o£ the back of the skull, including the basioccipital, exoccipital, 

 supraoccipital, stapes, imperfect opisthoticSj one pro-otic (text-fig. 3), basisphenoid 

 (text-fig. 6, B). 



The dimensions (in centimetres) of some of these bones are : — 



Basioccipital : width of condyle 6-7 



total length 6-5 



„ width 9-0 



length of neural surface 4'3 



Exoccipital : height 3-3 



Supraoccipital : extreme width (approx.) S'O 



height 4-9 



width of neural opening at lower end ... -9 

 width between inner edges of the foramina 



marked {for.) in text-fig. 2, C, D . . . . 5-0 



Stapes : greatest length 7"4 



„ thickness of inner end 5 1 



Basisphenoid : greatest length 6-4 



„ width 9-2 



R. 3013 (Leeds Coll. 91). A somewhat crushed skull and mandible. The bones of the occipital region 

 and palate are concealed or displaced, but the roof is fairlj^ well preserved : a few small 

 teeth (PI. I. figs. 1-6) and portions of sclerotic plates are preserved. Also seven caudal 

 vertebrae, a neural arch, nnmerous fragments of ribs, the right coracoid, and scapxila. 

 All the bones are fully ossified and seem to have belonged to an old individual. 

 The dimensions (in centimetres) are : — 



Skull : 



Approximate length 102-0 



Length from anterior angle of external nares to tip of snout 50'0 



Length of temporal fossa 13-0 



Width of temporal fossa (approx.) 7-5 



Width between posterior angles of squamosal . (approx.) 28"0 



