THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE IV. VOL. III. 



No. IV.— APRIL, 1896. 



OR,I<3-I2Sr^-Xj AETICLES. 



I Note on the Pelvis of Cutptoclidus Oxo.viensis (Phillips). 



By C. W. Andrews, B.A., B.Sc, F.G.S., 

 Assistant in the British Museum (Natural History). 



AMONG the Plesiosaurian remains recently mounted for ex- 

 hibition in the Reptile Gallery at the Natural History 

 Museum is a very fine pelvic-girdle belonging to a species of the 

 genus Cryptoclidus (Seeley), and forming part of the same skeleton 

 (Leeds Coll., R. 2616) as the pectoral-girdle recently described and 

 floured by the present writer. 1 These specimens are perhaps the 

 most perfect known, the bones being quite uncrushed, free from 

 matrix, and, except that they are cracked and broken to a slight 

 degree,' in much the same condition as if they had been obtained by 

 maceration from a recent reptile. They clearly belonged to an old 

 individual in which ossification had nearly reached its maximum: 

 this is shown (1) by the complete union of the coracoid and scapula 

 with one another in the middle line closing the coraco-scapular 

 foramen ; (2) by the sharpness of some of the edges of the bones, 

 e.g. of part of the anterior border of the pubis ; (3) by the great 

 solidity of the bones, and by the accuracy with which the pectoral 

 and pelvic elements fit together to form the glenoid and acetabular 

 cavities respectively, showing that the cartilage which separates 

 them in the young animal had been ossified. 



A mounted pelvis of Murcenosaiirus has been already described 

 and figured, 2 and if the present specimen be compared with it, it 

 will be seen that the differences between the two genera in this 

 part of the skeleton are considerable. Some of the more important 

 of these differences are pointed out below. 



Pubis.— The pubis is proportionately much wider from side to 

 side and shorter from before backwards than that of Murcenosaiirus. 

 Its anterior convex border is thin, except near the outer angle, where 

 it is thickened and produced into a short stout process, which is 



1 " On the Development of the Shoulder -girdle of a Plesiosaur {Cryptoclidus 

 Oxoniemis, Phillips, sp.) from the Oxford Clay": Ann. Mag. Nat. Hist., ser. 6, 

 vol. xv (1895), pp. 335-40, figs. 1 and 2. 



2 " On the Pectoral and Pelvic Girdles of Murcenosaiirus phcatus : Ann. Mag. 

 Nat. Hist., ser. 6, vol. xvi (1895), pp. 432-4, figs. 2 and 3. 



DECADE IV. VOL. III. NO. IV. 



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