H. GOVIEK SEELEY ON MATJISAUEUS GAKDNEEI. 



545 



rather smaller. The nutritive foramina become small circular 

 pits rather further apart. In all about 40 vertebrae have been 

 collected, of which about 14 are dorsal. 



So far as can be judged from the size of the vertebras, this species 

 was rather larger than the Elasmosaurus platyurus of Prof. Cope, 

 and is therefore the largest long-necked member of the order Ple- 

 siosauria which has been discovered. 



Since different writers have different methods of fixing the limits 

 of the several regions of the vertebral column, which results in an 

 undesirable confusion of characters of the species described, I venture 

 to offer the following diagram as a convenient guide to uniformity 

 in this particular, and as representing the characters of the divisions 

 of the vertebral column which I have described in this and other 



Diagram of the Divisions of the Vertebral Column in Plesiosaurs. 













Cervical. 











V- 



i 













Dorsal 









a 



i 







Caud 



bL 









A\ M unaLArches . 













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5 O O 



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YeurctlArclies 



It 





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G 



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Ifcl 



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Chevron bones. 



The curved line of small arches shows the position of the articulation for 

 the rib in the several regions of the body. 



Plesiosauria, in so far as they depend upon the position of the 

 articulation for the rib upon the centrum, or upon the neural 

 arch. 



Many of the dorsal ribs of Mauisaurus Gardneri have a strong 

 lateral crest at the proximal end, which makes the bone sub- 

 triangular in section. The fragments have a considerable curve ; but 

 none are sufficiently perfect for description. 



The bones of the pectoral arch are unfortunately imperfect. A 

 fragment of a coracoid is 13 inches long, and 10 inches wide, 

 as preserved; it does not show generic characters. The bones 

 met in the median line anteriorly, as usual, but appear to have 

 diverged posteriorly. Some fragments of scapula (?) appear to be not 

 unlike the scapula of Muramosaurus, but are imperfectly preserved. 

 Dr. Hector mentioned to me that he thought it possible for the scapulas 

 of Mauisaurus to have been convergent forward, and that they may 

 not have been directed outward as in his figure (Trans. New- 

 Zeal. Inst. vol. vi. 1874, pi. xxix.). 



The humeri and femora have both been found. From the great size 

 of the neck- vertebras, and the decrease in size of the dorsal vertebras, 

 as they approach the sacral region, I am disposed to conclude that 

 the humeri were larger than the femora. The humerus is 13 inches 

 long and imperfect proximally. Midway between the proximal and 

 distal ends the transverse width of the shaft is 7 inches. At about 

 4 inches from the proximal end the shaft is 3 j inches thick ; but 



