94 



THE SCIENCE OF LIFE. 



FIG 32. Arachnoidiscus Ehrenbergii. 



The Arachnoidiscus Ehrenbergii, (Fig. 32,) is common 

 on the coast of California, attached to sea-weed. Its gen- 

 eral appearance 

 is that of a glas- 

 sy pill-box. The 

 figure shows one 

 of the ends, or 

 frustules, covered 

 with delicate tra- 

 cery like a spi- 

 der's web, by 

 which the genus 

 gets its name, 

 from arachne, a 

 spider, and disc- 

 us, a disk. FlG - 33 -Heliopelta. 



