240 Mr. J. AV. Hulke. On the Shoulder Girdle 



Cor. 



FIG. 3. Shoulder girdle of Nothosaurus mirabilis. i natural size. From Zittel's 

 'Handbuch der Palseont.,' Bd. 3, Lief. 3, S. 476. (This is a reduced copy of 

 H. v. Meyer's, Fig. 1, Tar'. 34, ' Saurier des Muschelkalks.') 



long appeared to me conclusive of the correctness of H. v. Meyer's 

 interpretation of their homology ; and I am confirmed in this rectifi- 

 cation of my earlier view by instances of a similar behaviour of the 

 inner ends of the clavicles and interclavicle in certain Ichthyosauri a 

 from the Oxford clay obligingly brought under my notice by A. Leeds, 

 Esq., of Peterborough. Such relations obtain in Ophthalmosaurus 

 icemcus (Seeley, H. G.) (' Geol. Soc. Quart. Jour./ p. 396, et seq., vol. 

 30, 1874). 



Whilst in certain Ichthyosauria tbe relations of the inner ends of 

 the clavicles and interclavicle are in close accord with those obtaining' 

 in Nothosaurus, the relation of the outer ends of the clavicles to 

 the scapulae is different. 



Tn Ichthyosauria the clavicle tapers laterally, not widening, and its 

 outer end creeps up along the anterior border of the blade of the 

 scapula, splint- wise, nearly or quite to the full extent of the latter^ 

 with which, as already mentioned, it seems to have been only liga- 

 mentously connected. In Nothosaurus, however, the outer end of the 

 clavicle is united suturallj* to the body of the scapula, and at the 

 root of its ascending process, which most comparative anatomists, I 

 suppose, identify with the blade of the scapula. 



* The firmness of the suture (serrated) is shown by the fact that von Meyer found 

 several specimens in which tl e clavicle had broken off near the suture which still 

 held a fragment of the clavicle firmly knit to the scapula. 



