242 Mr. J. W. Hulkc. On the Shoulder Girdle 



to it in the Ichthyosaurian girdle in which he connects the mesial 

 end of the precoracoid with the antero-internal angle of the coracoid ; 

 whereas in Nothosaurus its mesial end would be separated from that 

 angle by a wide interval. 



That the process x was tipped with cartilage, and that the part of 

 the scapula marked x was clothed with cartilage is an inference not 

 drawn by H. v. Meyer himself who, from a study of several specimens, 

 says, the anterior border of the process x "bietet auf seinem 

 Yorderrande Unebenheiten dar, welche auf ein an dieser Stelle 

 angebracht gewesenes Band schliessen lassen;" and of x' that the 

 border is u von einer Beschaffenheit welche vermuthen lasst, dass 

 sie mit einem Band oder Muskel in Beriihrung gestanden hat."* 



From the above I think it will have become evident that the 

 grounds for the supposition of a precoracoid (cartilaginous) in Notho- 

 saurus are insufficient to establish this ; and if so, that the structure 

 of its shoulder girdle as regards this element fails to support the 

 hypothesis of a precoracoid in Ichthyosaaria. 



Gr. Baur has "no doubt that the Ichthyosauria possessed a small 

 cartilaginous sternum," He adds " the whole morphology of the 

 shoulder girdle strongly supports this opinion."! I am pleased to 

 find myself in accord with him on this matter, for I have long recog- 

 nised the great probability of the* presence of a cartilaginous sternal 

 plate behind the coracoids. I also have no doubt that the Ichthyo- 

 sauria had a cartilaginous supra-scapula. 



In connexion with the hypothesis of a precoracoid in the shoulder 

 girdle of Nothosaurus mirabilis, the small Nothosaurid Lariosaurus Bal- 

 sami Curioni deserves notice. Its shoulder girdle contains the same 

 elements as those in A 7 , mirabilis, and their forms and arrangements are 

 similar, the chief difference being the absence of the large process so 

 conspicuous at the anterior margin of the coracoid in the latter. In 

 the more simple form of this bone there is a closer resemblance to 

 Plesiosauria than is shown by N. mirabilis. The annexed figure 

 from C. Zittel's ' Pal.' affords the means of comparison of the girdles 

 of Lariosaurus Balsami with those of Plesiosaurus and N. mirabilis. 

 In an upper view of a complete skeleton of Lariosaurus Balsami 

 (original in Munich Museum), figured by C. Zittel, ' Pal.,' vol. 3, p. 485, 

 fig. 461, the dorsal process of the scapula is seen in natural position 

 above the glenoid mass, rising with a strong backward slant (d.pr.). 



In Anarosaurus pumilio (W. Dames) another small member of 

 the same family, the coracoid also has a simple form, and its anterior 

 border wants the process characteristic of N. mirabilis. Again, in 

 Neusticosaurus pusillus (H. G. Seeley), another member of this family, 



* Meyer, H. v., op. cit., p. 45. 



f Baur, G., ' On the Pelvis of the Testudinata.' Boston, 1891. Reprint fronv 

 the ' Journal of Morphology,' vol. 4, No. 3 ; p. 34. 



