in Ichthyosauria and Sauropterygia. 243 



Int. 



d.pr. 



Cor. 



FiG. 5. Shoulder girdle of Lariosaurus Balsami Curioni (ventral view). From 

 Zittel, op. cit. y S. 488, fig. 462. d.pr., dorsal process of scapula. 



the relations of the anterior ventral ray and scapula are in principle 

 identically the same as in N. mirabilis ; the anterior ray articulating 

 with the scapula, and not contributing to form the fossa glenoidalis. 

 The coracoid, however, repeats the simpler form seen in Lariosaurus 

 Balsami and in Anarosaurus pumilio. 



Thus if Macromerosaurus be only a yonng example of Lariosaurus, 

 and if Pachypleura is Neusticosaurus, as C. Zittel, W. Dames, and 

 some others suppose, we have the fact that none of the family of 

 Nothosauridae, unless N. mirabilis, lend any support to the idea of the 

 existence of a precoracoid, but rather the contrary ; and those points 

 in N. mirabilis which have been cited in support of the presence of a 

 precoracoid in this, and so in Ichthyosaurus, are, as I have suggested, 

 capable of other and simpler explanation. 



Another reason assigned by Professor H. G. Seeley for introducing 

 a cartilaginous precoracoid into the Ichthyosaurian shoulder girdle is 

 " it brings the shoulder girdle of Ichthyosaurus into harmony with 

 that of the Anornodontia, because they correspond in the form of the 

 scapulas, the position and forms of the clavicles, interclavicles, and 

 coracoids ; so that if the Anomodont precoracoid were unossified the 

 differences from Ichthyosaurus would be small, except that the Anom- 

 odonts develop an epiclavicle of Labyrinth odont type." 



The principal Anomodont remains available for the comparison 

 are, I take it for granted, those preserved in the British Museum, 

 chiefly from African sources. They include several dissociated more 

 or less imperfect scapulas and coracoids, of which the more important 

 pieces were figured by R. Owen in his ' Catalogue of S. African 

 Reptilia,' 1876, PI. 69, figs. 5, 6, 8, 9, and PI. 70, fig. 1. They com- 

 prise also the remains of Pareiasaurus, described by Professor H. G. 

 Seeley, ' Phil. Trans.,' B. 1888, p. 59, et seq., PI. 20, figs. 1, 2 ; those 

 of Keirognathus cordylus, described by this author, ' Phil. Trans.,' B, 



