646 



SKELETON. 



thoracic rib, invites the reason to name all 

 these pieces as costiform, wherefore should 



Fig, 468, 



The cervical spine of the Ornithorhynchus, 



Showing that b the coracoid bone, d the clavicle, 

 and e the sternal end ,of the rib, are serial homo- 

 logues. 



we not regard -the pieces 1,2,3,4,5, con- 

 tinued serially into the rib of 6, as being cos- 



tiform likewise, despite the fact that anato- 

 mists have already regarded the pieces 1 and 

 2 as the coracoid and clavicular bones ? Do 

 we not see in jig. 469. that the parts 1, 2, 

 3, 4, 5 point to the parts a, b, c, d, e, just as 

 the part 6 points to the part/? If it be 

 said that the parts 1 and 2 (the coracoid and 

 clavicle), being disconnected from the cervical 

 ribs (a and 6) are therefore to be regarded as 



3Ucintities unrelated originally to a, b y I must 

 oubt whether this can efface from the rational 

 mind the belief that the now separated pieces 

 a, 1 or b, 2, taken as whole quantities, equal 

 the costo- sternal form/, 6. 



Whether or not the above-mentioned 

 interpretation as to the origin of the bones 

 called clavicle and coracoid be true, must 

 be seen through the facts as they are here 

 recorded : but be this interpretation as it 

 may, I plainly affirm that the comparative 

 anatomist has no positive evidence, near 

 or remote, directly or indirectly, either by 

 a similarity of structure, or function, or po- 

 sition, or aught else, to regard the cora- 



Fig. 469. 



The cervical spine of a Lizard, 



In which the cervical ribs, a, b, c, d, e, point to the coracoid bone 1, the clavicle 2, and the 

 pieces marked 3, 4, 5, as their proper continuations, and just as the sternal rib, 6, continues 

 the vertebral rib, /, to the sternal median line. 



coid process of the human scapula as the 

 counterpart of the bone (d jig. 466.) called 

 coracoid in the bird, or of 2, the coracoid 

 of jig. 469., the reptile.* The anatomist 

 may just as well call the sternum a series of 

 vertebrae (a statement by-the-by which some 



* On referring to the " Homologies of the Verte^ 

 brate Skeleton," I find, in the section " General 

 Homology," the following opinion, advanced re^ 

 specting the coracoid bone, that it " is always deve- 

 loped from an independent osseous centre (a rudi- 

 mental representative of the haemapophysis), which 

 coalesces with the pleurapophysis in mammalia, and 

 only attains its normal proportions completing the 

 arch with the haemal spine (episternum) in the 

 monotremes." The reader will not, perhaps, com- 

 prehend the author's meaning in this sentence, taken 

 separate from the flowing context of the work 

 cited. The meaning of the sentence is this : The 

 scapulary organ is referred to the occipital vertebra, 

 as the haemal arch of this segment of the skull, the 

 scapula is interpreted as its pleurapophysis or rib, 

 and the coracoid bone (process) is accounted the 

 haemapophysis appended to the costiform scapula, 

 and thus the typical occipital vertebra is formed. 

 Although I regard the work from which I have 

 quoted to be a lasting monument of learning, re- 

 search, and inductive reasoning a worthy effort in 

 a great cause still I cannot concur in the opinion 

 which that work announces respecting the relation 

 between the acapulary member and the occipital 

 vertebra. 



have made)*, as to say that there is identity 

 between the human coracoid process and the 

 bird's coracoid bone. However endless may 

 be the whole account of specific difference be- 

 tween bone and bone, and between one skele- 

 tal form and another, still there does appear 

 happily some well-marked limits to the homo- 

 logies. No one, for example, will torture the 

 bone named scapula into an identity of cast 

 with the bone named rib f ; and I believe that 

 the same absolute difference is possible to be 

 pointed out between the coracoid process of 

 the human scapula and the bone named cora- 

 coid in the bird, or that bone so named in the 

 chelonian reptile. The coracoid process of 

 the human scapula is an elemental part proper 

 to the scapula, just as the centrum is a part 

 proper to the vertebra. The bone called 

 coracoid (d, fig. 466.) in the bird abuts 

 against that part of the bird's scapula where 

 the coracoid process usually appears in 

 mammal scapulae; but this coracoid bone is 

 not representative of the -mammal coracoid 



* De Blainville, Meckel, and Cams entertain this 

 opinion, which certainly has no support from natural 

 evidence. 



f It is true, however, that this very opinion re- 

 specting the scapula is advanced by the distin- 

 guished author of the " Homologies," &c. 



