ZOOLOGY 



Ammonites, of which two thousand fossil (extinct) species are 

 known, ranging through many geological ages. 



Fig. 213. — Xautilus pompiliiis. the Pearly Nautilus. Median section, c, outer- 

 most eliamber whose bottom is fomted by the septum, sc ; .s. siphon travers- 

 ing all compartments ; e, eye ; h, hood ; m, part of mantle, reflected over 

 the shell ; /, lobes enclosing tentacles (0 : si. incomplete funnel ; mu, shell 

 muscle ; n, gland secreting the capsules for eggs. After Owen. 



