AND CLASSIFICATION. 27 
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 concen- 
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. the backbone, — while Baer, who 
is an embryologist, signifies in his their mode of 
growth also. He knew what Cuvier did not 
