Gallery 
VIII. 
()0 GUIDE TO THE -FOSSIL INVEKTEBEATE ANIMALS. 
since the 'arms remain only live liowever many times eacli 
may branch. 
Anal lithe 
^ .pinnules 
Pig. 28. — A simple 
form of Criuoid, 
Jiotryocrinus dc- 
cadactylus, from 
the W e n 1 0 0 k 
Limestone ; re- 
constructed from 
-Cirri specimens in the 
' Museum. (Table- 
case 32.) 
. C? o 
The arms serve not only for collecting food but also for 
respiration. The hydraulic system already mentioned extends 
