ON THE VERTEBRATE SKELETON. 17-J 



In proposing a definite name for each distinct bone, declaratory of its 

 special homology throughout the vertebrate kingdom, I have sought earnestly 

 to reduce the amount of reform to the minimum allowed by the exigences 

 of the case. Agreeably with Aphorism III. of the ' Philosophy of the In- 

 ductive Sciences' (p. lxvii.), the nomenclature of anthropotomy forms the 

 basis, and all the names given to parts by one or other of the great French 

 anatomists have been accepted, with the modifications of a Latin or an En- 

 glish termination, wherever such names had not been applied, as is the case 

 with some proposed by Geoffroy St. Hilaire, to two different parts. In sub- 

 stituting names for phrases, I have endeavoured, conformably with another 

 of Dr. Whewell's canons (Aph. XVII. op. cit. p. cxvii.), to approximate the 

 sound of the name as nearly as possible to those of the leading terms of the 

 definition or phrase, as e. g. alisphenoid for ' ala media, &c. sphenoidalis ' and 

 for ' grande aile du sphenoide ' ; orbitosphenoid for ' ala superior seu orbi- 

 talis, &c. sphenoidalis,' and for ' aile orbitaire du sphenoide*.' 



The corresponding parts in different animals being thus made namesakes, 

 are called technically ' homologues.' The term is used by logicians as syno- 

 nymous with ' homonyms,' and by geometricians as signifying ' the sides of 

 similar figures which are opposite to equal and corresponding angles,' or to 

 parts having the same proportions t : it appears to have been first applied in 

 anatomy by the philosophical cultivators of that science in Germany. Geof- 

 froy St. Hilaire says, " Les organes des sens sont homologues, eomme s'ex- 

 primerait la philosophie Allemande ; c'est-a-dire qu'ils sont analogues dans 

 leur mode de developpement, s'il existe veritablement en eux un meme prin- 

 cipe de formation, une tendance uniforme a se repeter, a se reproduire de la 

 meme fac.on J." The French anatomist, however, seems not rightly to 

 define the sense in which the German philosophers have used the term : 

 there is a looseness in the expression ' analogous in their mode of develop- 

 ment,' which may mean either identical or similar, and also different kinds of 

 similarity. Parts are homologous in the sense in which the term is used in 

 this Report, which are not always similarly developed: thus the 'pars occi- 

 pitalis stricte sic dicta,' &c. of Soemmerring is the special homologue of the 

 supraoccipital bone of the cod, although it is developed out of pre-existing 

 cartilage in the fish and out of aponeurotic membrane in the human subject. 

 I also regard the supraoccipital as the serial homologue of the parietal and 

 the midfrontal, although these are developed out of the epicranial membrane 

 in the fish, and not out of pre-existing cartilage, like the supraoccipital. 

 The femur of the cow is not the less homologous with the femur of the cro- 

 codile, because in the one it is developed from four separate ossific centres, and 

 the other from only one such centre. In like manner the compound mandi- 

 bular ramus of the fish is the homologue of the simple mandibular ramus of 

 the mammal, as the compound tympanic pedicle of the fish is homologous 

 with the simple tympanic pedicle of the bird, the differences expressed by 

 the terms ' simple ' and ' compound ' depending entirely on a difference of 

 development. 



Without knowing the precise sense in which Geoffroy St. Hilaire under- 



* The happy facility of combination which the German language enjoys has long enabled 

 the very eminent anatomists of that intellectual part of Europe to condense the definitions of 

 anthropotomy into single words ; but these cannot become cosmopolitan ; such terms as 

 ' Hinterhauptbeinkorper,' ' Schlafbeinschiippen.'and 'Zwischenkiemendeckelstiick,'are likely 

 to be restricted to the anatomists of the country where the vocal powers have been trained 

 from infancy to their utterance. 



t This is the sense in which the term is defined in the French Dictionary and in our 

 Johnson's Dictionary. 



X Annales des Sciences Naturelles, torn. vi. 1825, p. 341. 



