in Iclitliyosauria and Sauropterygia. 



' Pr.c 



249 



O.fas. 



Cor. 



FIG. 9. Shoulder girdle of Emys Europcea. O.fas., obturator fascia; f.p.n., 

 foramen for nerve. From Hoffmann. Bronn's ' Klassen, Kept.,' Bd. 1, Taf. 8, 

 fig.7 f 



single, angulated bone forms the upper or the anterior part, the 

 coracoid furnishing the posterior part. 



Professor H. G. Seeley says, in his recent paper, "There is no 

 conclusive evidence of the mutual relations of the scapulo-precoracoid 

 to the glenoid cavity in Chelonia." If by this he means that no 

 evidence exists to show whether one only or both of the components 

 of the apparently single bone lie thus designates enter into the com- 

 position of the glenoid fossa, this statement is, I venture to submit, 

 scarcely justifiable, in view of the embryological investigations of 

 that extremely careful, painstaking observer, H. Rathke, who, 

 writing of the Testudinate shoulder girdle, says : "In the anterior 

 piece (i.e., the united scapula and coracoid), however, I found in the 

 embryo of Chelonia, and in the young of Chelonia imlricata, Trionyx 

 Gangeticus, and Terrapene tricarinatus, that each limb had a particular 

 bony sheath, and that the two sheaths were nowhere confluent, but 

 only at one side of the angle which the two limbs composed they had 

 very closely approached one another ; whereas at the outer side of 

 this angle they were still distant from each other, and the entire 

 process projecting from the latter (the angle), and which contained 

 the joint-hollow consisted only of cartilage." " In the young Sphargis 

 the two bony sheaths had reached one another at the inner side of 

 the angle formed by the two limbs of the anterior shoulder piece, and 

 had here coalesced, leaving, however, still uncovered the outer side of 

 the angle and the articular process."* 



From these observations of H. Rathke, made in different families 

 of Testy dinata, which are in accord with an observation long pre- 

 viously made by Cuvier in a very young Chelonia, it may very fairly 

 be assumed that in this order generally ossification begins separately 



* Rathke, H., ' Ueber die Entwickelung der Schildkroten,' p. 137. 



