526 On the Structural Relations of Organized Beings. 



again, p. 377: — " These clavicles are the homologues of the 

 os furcatorium in the Bird." And in the note, same page: — 

 " For a full and elaborate discussion of the various opinions 

 which have been offered respecting the homology or significa- 

 tion of the complicated apparatus of the shoulder," &c. I 

 could easily multiply instances in which the term homology 

 has been applied, both substantively and adjectively, in the 

 sense recommended by Mr. Strickland. I have been in the 

 habit of defining, in my Introductory Lecture, the terms ho- 

 mology and analogy, as in the Glossary appended to the Lec- 

 tures on Invertebrata, published in 1843, and of illustrating 

 their meaning in comparative anatomy, by reference to the 

 skeletons of the Bird and the Draco volans. The fore-limb of 

 the Dragon being composed of essentially the same parts as the 

 wing of the Bird, is homologous with it ; but the wing or para- 

 chute of the Dragon, having a similar relation of function, is 

 analogous to the wing of the Bird. But in thus illustrating the 

 term homology, I have always felt and stated that I was merely 

 making known the meaning of a term introduced into com- 

 parative anatomy long ago, and habitually used in the wri- 

 tings of the philosophical anatomists of Germany and France. 

 Geoffroy St. Hilaire also, in defining the term, acknowledges 

 its source: — " Les organes sont homologues comme s'expri- 

 merait la Philosophic Allemande; e'est a dire qu'ils sont ana- 

 logues dans leur mode de developpement," &c. — Annates des 

 Sciences, torn. vi. 1825, p. 341. 



I have gone perhaps a little further than Oken and Geof- 

 froy in defining the different kinds of * homology/ which ap- 

 pear to me to be three, viz. i general,' • serial,' and * special.' 

 General homology is the relation in which a part or series of 

 parts stands to the ideal or fundamental type; and thus, when 

 the basilar process of the occipital bone in Anthropotomy is 

 said to be the ' centrum ' or • body of the last cranial vertebra,' 

 its general homology is enunciated. When it is said to re- 

 peat, in its vertebra or natural segment of the skeleton, the 

 body of the sphenoid bone, the body of the atlas, and the suc- 

 ceeding vertebral bodies or centrums, its serial homology is 

 indicated. When the essential correspondence of the basilar 

 process of the occipital bone in Man with the distinct bone 

 called ' basi-occipital ' in a crocodile or a fish is shown, its 

 special homology is determined. 



Vicq d'Azyr began the study of ' serial homologies ' in his 

 ingenious memoir on the parallelism of the fore and hind 

 limbs, in the Memoirs of the French Academy, 1788. 



* Homologous parts' are, indeed, in one sense, 'analogous 

 parts,' having like relations, as being repetitions of the same 



