±9 
SUB-KINGDOM 
ARTICULATA or ARTIIROPODA. 
CRUSTACEA. 
TRILOBITA. 
During the earlier Palaeozoic epochs to near the close of the 
Silurian ages, Trilobites formed the highest grade of organized 
beings (except perhaps the Cephalopoda), and were frequently very 
abundant. They were the crabs and lobsters of those times ; their 
nearest living representative being probably the king-crabs of our 
own coasts. Trilobites make their appearance among the very 
earliest forms of fossil remains, and continue to the Coal period ; 
at the close of which time they became extinct. They were ex- 
tremely abundant, and in fact formed the principal animal life 
during the earlier Primordial epochs, although in many places 
their remains are entirely fragmentary. The following illustrations 
will give an idea of some of their forms. 
