86 



PICTURESQUE SKETCHES 



close of the first epoch. These animals are called 

 TriloUtes. (See figures 8, 9, 10.) 



The trilobites, of which there is a consider- 



Fig. 9 



able number of 

 distinct generic 

 forms in the 

 older rocks, were 

 provided with a 

 large semicircu- 

 lar or crescent- 

 shaped shield, 

 completely de- 

 fending the head; 

 their body was 

 in like manner 

 secured from the 

 attack of an ene- 

 TRILOBITES.* my by a number 



of plates or segments moving readily upon one 

 another, like the horny plates of a shrimp ; and 

 the tail was armed with a similar series. The ani- 

 mal seems not to have had antennae, and to have 

 possessed short and rudimentary legs ; but on the 

 head were placed a pair of large conical projections 

 covered with eyes, by the help of which any ap- 

 proaching danger might be seen ; and the power of 

 rolling itself into a ball (see figure 10), which it pos- 

 sessed in common with the wood-louse and the chiton, 

 enabled this creature, no doubt, to escape the attack 

 of many of its enemies. It is not very easy either to 

 make out the habits of an animal of such singular 



* 8, Homalonotus armatus. 9, Trinucleus Caractaci. 10, Calymenc 

 Blumenbachii. 



