THORAX AND RIBS. 39 



double articulating surface ; the inferior part of which belongs to the cunei- 

 forme, the superior to the lower extremity of the ulna. The postero-inferior 

 face is quite rough and irregular, and presents a superior and inferior tube- 

 rosity, with an excavation between them. 



Second Eaxge. Trapezium (Plates XL and XII. K). — This bone lies at second 



Range. 



the internal side of the range, and might be mistaken for a metacarpal ; 



but, on examination, it is found not to possess the enlarged extremities and 



contracted body of a metacarpal. It is situated between the trapezoides 



and first metacarpal bone. Its superior surface is oblique, descending from 



within outwards, corresponding to and articulating with the trapezoides. 



The inferior surface is flattened, to articulate with the upper surface of 



the first metacarpal. The internal face is rounded and very irregular ; the 



external, somewhat flattened, but excavated in the middle for ligamentary 



attachments. 



Trapezoides (Plate XL I). — This bone is situated between the scaphoi- Trapezoi- 

 des. 

 des and trapezium on the inner side, and the os magnum on the outer. Its 



anterior face is quadrangular. The posterior face terminates in a tubercle ; 

 by the side of which is situated a large, deep excavation, which it forms, in 

 common with the os magnum, for the reception of a strong ligament. It is 

 articulated superiorly with the scaphoides and semi-lunare, inferiorly with 

 the second metacarpal, internally with the trapezium, externally and prin- 

 cipally with the os magnum, into which it is received, and with which it is 

 firmly interlocked. 



Os Magnum (Plate XL H). — This bone has nearly a cubical form. o s 



Magnum. 



Its anterior rough face is quadrangular; its superior wholly occupied by 

 an articulating surface for the semi-lunare ; its posterior, large and irregu- 

 lar, presents various tubercles ; its inferior has a double articulating surface 



