1871.] 



169 



[Wilder. 



a reform. The changes proposed are, as far as possible, in accord- 

 ance with the following requirements of technical terms : — 



1. Classic Derivation; 2. Capacity for inflection; 3. Brevity; 

 4. Independence of context for signification; 5. Non-ambiguity to 

 the ear as well as to the eye; 6. Previous use in a kindred 

 sense. I cannot hope to have satisfied all the requirements in every 

 case, and ask for corrections and amendments. I admit all the ob- 

 jections which have been urged against new terms; but am con- 

 vinced that some change must be made before homology can be the 

 exact science which it is capable of becoming; and I would refer to 

 Agassiz (200, 3, 69), Goodsir (237, 2, 83), Owen (63, 1, xm) and 

 Strauss-Durckheim (331, 1, xv) in support of a correct system of 

 nomenclature. 



The accompanying dia- 

 gram presents the dorsal 

 surface of a vertebrate ani- 

 mal in what may be called 

 a neutral or indifferent con- 

 dition as to both attitude 

 and structure ; although 

 some details are introduced 

 for the purpose of employ- 

 ing this figure in other 

 parts of the discussion. 

 The animal is shown as a 

 circular disk, the " ger- 

 minative area," at the time 

 it presents the two charac- 

 teristic and common fea- 

 tures of all vertebrates. 



First : — A discrimina- 

 tion between the cephalic 

 and the caudal regions by 

 the formation of the ce- 

 phalic and caudal hoods; 

 and it is of great signifi- 

 cance that, (with the Tur- 

 tle at least, according to 

 Agassiz, 200, 2, 537-539) 

 this occurs prior to the 

 separation into a right and 

 a left half. 



