THE SKELETON 79 



In the great majority of Eeptiles a similar aperture (ect- 

 epicondylar foramen) is found on the outer side of the humerus, 

 (Fig. 55, A ii), and in some both foramina are present. These 

 are in both cases nerve canals, which fact suggests that they may 

 not have arisen either among Amphibians or Eeptiles, but rather 

 among animal forms phylogenetically still older. 



[In consideration of the facts already recapitulated (pp. 68-70) con- 

 cerning the comparative anatomy and development of the vertebrate limb- 

 skeleton, the probability that these condylar foramina may be indicative of 

 a] polymeric origin of the basal segments of the limb-skeleton must not be 

 overlooked, for, in the Ontogeny of the Sharks and Sturgeons, these latter can 

 be traced to an origin by concrescence from parallel cartilaginous rays. If this 

 be the meaning of the foramina, the fact that among living Reptiles they are 

 most marked in the most primitive genus (Hatteria) is the more interesting. 



I have elsewhere l raised the question whether the foramina nutritia, 

 occurring in the long bones of the limbs, may not have had a similar origin. 

 A wide field is here open for research, in which palaeontology should play an 

 important part. 



Special interest attaches to the skeleton of the human hand, 

 and there is still abundant room for 

 further investigation concerning it. 



Taking first the carpus, the re- \\ o j3 



semblance of that of Man to the \ V U JS / 

 carpus and tarsus of the tailed Am- \ A jj S fif 

 phibians is most striking. In its V^ CV ^ I? /> 

 proximal row there are the three w T ell- A y^ U CJ // 



known bones, the radiale (scaphoid = ^<^\^^ 



tibiale in the pes), the intermedium /-^ Q 



(lunar), and the ulnare (cuneiform = V^T 



fibulare in the pes), cf. Figs. 56, 57, 

 59, 60. In the distal row, counting 

 from the inner or radial face, lie the 



first carpale (trapezium = 1st tarsal or 



. . ,, N ,, , FIG. 56. SKELETON OF THE HIND- 



ento-cuneiform in the pes); the 2nd car- LlMB OF A TAILED AMPHIBIAN 



pale (trapezoid = 2nd tarsale or meso- (Spderpesfuscus) 



> ^ . <//., tibia ;/&., fibula; (., tibiale; 



cuneiform in the pes) ; the 3rd carpale /, intermedium ; f, fibulare ; 

 (magnum = 3rd tarsale or ecto-cunei- c,_ceutraie ; 1-5, tarsalia; itov, 

 form in the pes) ; and the 4th carpale 



of the skeleton (cf. Rep. Internal. Medic. Congress, Loud. 1881). A remarkable 

 outcome of the latter tendency has been recently described by Griinbaum, in the 

 discovery of a ligament which, bridging over the posterior condylar foramen, forms a 

 tunnel for a branch of the occipital artery, and, by ossification, may form "a ring of 

 bone projecting downwards from the lower surface of the occiput " (Jour. Anat. and 

 Phys., vol. xxv. p. 428, and Macalister, ibid. p. Hi.).] 

 1 Das Gliedmassen Skelet (see ante, p. 74, footnote). 



