670 



SKELETON. 



join each other at the common median line The pair of scapulae (B) forms a symmetrical 



(Vz, b). From these laminae we find jutting figure : both scapulee (c, c) are evidently 



out laterally the exogenous transverse pro- similar to each other, and also to the lamina? 



cesses (d, d) t each of which is tipped by an (c, c) of the vertebra (A).* From each sca- 



epiphysis. 



pula we find projecting laterally an exogenous 

 Fig. 489. 



-C" 



Showing that the pair of scapulas and the pair of iliac bones, compared with the pair of 

 vertebral laminae, prove a homological relation, and also that the heads of the humerus", 

 the femur, and the rib are similar to one another. 



process (d, d), which is commonly named 

 acromial process, and each is tipped with an 

 epiphysis also. These acromial processes 

 evidently correspond to the transverse pro- 

 cesses (d, d) of the vertebra (A). 



The pair of iliac bones (c) likewise forms a 

 symmetrical figure when laid crest to crest. 

 These two iliac bones (c, c) are homologous, 

 not only to each other, but to the two sca- 

 pulae (B), and to the two vertebral laminae of 

 A. From each iliac bone there projects late- 

 rally the process d, d, which answers to the 

 acromion process d of B, and to the transverse 

 process d of A. The process d of c is named 

 anterior inferior process of the ilium, and it 

 is tipped with an epiphysis. 



The law of symmetry becomes the expo- 

 nent of the structural identity existing between 

 the figures A, B, and c ; for we find the com- 



* If this homological relation which I point out 

 as apparent between the pairs of scapulas and iliac 

 bones, with the pair of vertebral laminaa, be true, 

 then the homological relation which Professor Owen 

 describes as existing between the scapulas and the 

 ribs, as also between the iliac bones and the ribs, 

 cannot at the same time be received as a true 

 doctrine. 



mon median line (a, b) bisecting them through 

 their conjoined bases. The opposite halves 

 of each of these figures form symmetrical 

 figures, but it is also true that the half of each 

 is asymmetrical. 



Now, as the rib (?,/) articulates with each 

 side of the vertebra (A), and is overhung by 

 the transverse process (d), so the humerus (f,/) 

 articulates with each side of the scapular 

 form (B), and is overhung by the acromion 

 process (d). In just the same relations, the 

 thigh-bone (e,/) of the iliac form (c) is over- 

 hung by the anterior inferior spinous process 

 (of). It becomes evident, therefore, that the 

 heads of the rib, the humerus, and the femur 

 correspond ; and this correspondence is mani- 

 fested, not only by the position occupied by 

 each, but likewise by the genetic character of 

 all three ; for the parts of the rib (*,/) of A are 

 epiphyseal, the same of the parts (*,/) of the 

 humerus of B, and the same of the parts (e,f) 

 of the femur of c. The articular facets (/) 

 of the rib, the humerus, and the femur corre- 

 spond; the tuberosity (e) of the rib, the 

 humerus, and the femur likewise correspond. 

 The spinous borders of the opposite vertebral 

 laminae of A, the basis of the scapulae (B), and 



