xiv PREFACE. 



practice is necessary to acquire the knack of applying the new 

 tool. But in this acquisition a small capital of trouble will have 

 been invested with a sure return of large profits. A single sub- 

 stantive term is a better instrument of thought than a paraphrase. 1 

 But the substitution of such terms for definitions is still more 

 advantageous when they are susceptible of becoming adjectives by 

 inflection. Thus the term ' notochord ' for ' chorda dorsalis ' or 

 ' dorsal chord ' enables one to predicate of species or groups of 

 vertebrates as being ' notochordal ; ' that single epithet implying 

 that the embryonal body in question is, in them, persistent. A 

 like advantage cleaves to ' myelon ' for ' chorda spinalis ' or 

 e spinal chord ;' the Physiologist, e.g., can then speak of 'myelonal 

 functions,' and the Pathologist of 'myelonal' disease, with the cer- 

 tainty of being understood to signify properties and affections of 

 the ( spinal chord ;' not, as in ' spinal disease,' that of its case, or 

 ' spinal column.' In regard to the part so called and its con- 

 stituent e vertebra?,' their modifications are so many, so charac- 

 teristic, so important, especially in the application of Anatomy to 

 Palaeontology, that I was early compelled in the latter kind of 

 labour to substitute single pliable terms for the phrases ' trans- 

 verse process,' ' oblique ' or ' articular process,' ( body of the 

 vertebra,' ' vertebral lamina,' ' vertebral rib,' ' sternal rib,' &c, 

 by which the parts of the ' vertebra ' were then designated. 



But the single names of parts and constituents of the skeletal 

 segment called ' osteocomma ' or ' vertebra ' have not merely the 

 advantage above illustrated, as where the adjective ' neurapo- 

 physial ' can be applied to a ' ridge,' notch, or ' foramen,' in the 

 vertebral lamina (neurapophysis) ; the vertebral terminology in 

 use in the present Work indicates a profound truth which is 

 hidden by the language of anthropotomy. The terms ' pleur- 

 apophysis' and ' hoemapophysis ' imply parts of the segment corre- 



1 ' Superoccipital,' e.g., for ' pars occipitalis stricte sic dicta partis occipitalis ossis 

 spheno-occipitalis ' of the eminent anthropotomist Soemmering. (See Table of 

 Synonyms, &c, appended to Vol. II.) Similarly, in the present Work, I use the word 

 ' Vertebrate ' as a substantive. We do not speak of a ' Confederate ' animal, and the 

 added word is as unnecessary in regard to the ' Vertebrate ' one. 



