618 



tiou is manifeutly insufficient. If the data put before him do not 

 bear out tlie inference, it is competent for every logical reader to 

 say so. 



From this stand-point, then, we venture to criticize some of 

 Professor Owen's osteological theories. For his knowledge of 

 comparative osteology we have the highest respect. Wc beliere 

 that no living man has so wide and detailed an acquaintance with 

 the bony structure of the Vertebrata. Indeed, there probably has 

 never been any one whose information on the subject was so nearly 

 exhaustive. Moreover, we confess that nearly all we know of this 

 department of biology has been learnt from his lectures and writ- 

 ings. We pretend to no independent investigations, but merely to 

 such knowledge of the phenomena as he has furnished us with. 

 Our position, then, is such that, had Professor Owen simply cnou- 

 ciated his generalizations, we should have accepted them on his 

 authority. But he has brought forward evidence to pfove them. 

 By so doing he has tacitly appealed to the judgments of his readers 

 and hearers— has practically said, " Here are the facts ; do they 

 not warrant these conclusions ?" And all we propose to do, is Vo 

 consider whether the conclusions are warranted by the facts brought 

 forward. 



Let us first limit the scope of our criticisms. On that division 

 of comparative osteology which deals with what Professor Owen 

 distinguishes as " special homologies," we do not propose to enter. 

 That the wing of a bird is framed upon bones essentially parallel to 

 those of a mammal's fore-limb ; that the cannon-bone of a horse's 

 leg answers to the middle metacarpal of the human hand ; that 

 various bones in the skull of a fish are homologous with bones in 

 the skull of a^man — these and countless similar facts, we take to be 

 well estabhshed. It may be, indeed, that the doctrine of special 

 homologies is at present carried too far. It may be that, just as 

 the sweeping generalization at one time favoured, that the embryonic 

 phases of the higher animals represent the adult forms of lower 

 ones, has been found untrue in a literal sense, and is acceptable 

 only in a qualified sense ; so the sweeping generalization that the 

 skeletons of all vertebrate ahimals consist of homologous parts, will 

 have to undergo some modification. But that this generalization 

 is substantially true, all comparative anatomists agree. 



The doctrine which we are here to consider, is quite a separate 

 one — that of " general homologies." The truth or falsity of this 

 may be decided on quite apart from that of the other. Whether 

 certain bones in one vertebrate animal's skeleton correspond with 

 certain bones in another's, or in every other's, is one question ; and 

 whether the skeleton of every vertebrate animal is divisible into a 

 series of segments, each of which is modelled after the same type, 

 is another question. While the first is answered in the affirmative, 



