AND CLASSIFICATION. Zl 



which all the parts converge from the periphery 

 or circumference of the animal to its centre. 

 Cuvier only reverses this definition in his name 

 of Radiates, signifying the animals in which all 

 parts radiate from the centre to the circumfer- 

 ence. By Massive, Baer indicated those animals 

 in which the body is undivided, soft and concei: 

 trated, without a very distinct individualization 

 of parts, — exactly the animals included by Cu- 

 vier under his name of Mollusks, or soft-bodied 

 animals. In his selection of the epithet Longitu- 

 dinal, Baer was less fortunate ; for all animals 

 have a longitudinal diameter, and this word was 

 not, therefore, sufficiently special. Yet his Lon- 

 gitudinal type answers exactly to Cuvier' s Articu- 

 lates, — animals in which all parts are arranged 

 in a succession of articulated joints along a lon- 

 gitudinal axis. Cuvier has expressed this jointed 

 structure in the name Articulates ; whereas Baer, 

 in his name of Longitudinal, referred only to the 

 arrangement of joints in longitudinal succession, 

 in a continuous string, as it were, one after an- 

 other, indicating thus the prevalence of length as 

 the predominant diameter of the body. For the 

 Doubly Symmetrical type his name is the better 

 of the two ; since Cuvier's name of Vertebrates 

 alludes only to tin backbone, — while Baer, who 

 is an embryologist, signifies in his their mode of 

 growth also. He knew what Cuvier did not 



