THE SILURIAN BEACH. 
63 
mals is very complete ; and their attitudes are 
often so natural, and the condition of all then- 
parts so perfect, that one would say they had 
died yesterday rather than countless centuries 
ago. 
Their geological history has been very thor- 
oughly studied ; not only are we familiar with 
all their adult characters, but even their embry- 
ology is well known to naturalists. It is, indeed, 
wonderful that the mode of growth of animals 
which died out in the Carboniferous period should 
be better known to us than that of many living- 
types. But it is nevertheless true that their em- 
bryonic forms have been found perfectly pre- 
served in the rocks, and Barrande, in his “ Sys- 
teme Silurien de la Boheme,” gives us all the 
stages of their development, from the time when 
the animal is merely sketched out as a simple 
furrow in the embryo to its mature condition. 
So complete is the sequence, that the plate on 
which their embryonic changes are illustrated 
contains more than thirty figures, all represent- 
ing different phases of their growth. There is 
not a living Crab represented so fully in any of 
our scientific works as is that one species of Tri- 
lobite whose whole story Barrande has traced 
from the egg to its adult size. Such facts should 
make those who rest their fanciful theories of the 
origin and development of life on the imporfcc- 
