THE DAWN OF LIFE 



173 



strong reasons have been assigned for giving them 

 an intermediate place, as allied to those curious 

 communities of humble animals possessing simple 





•y.. »«*•■• y.—^*—"' 



Fig. 44. — Structures of Stromatopota. 



{a) Portion of oblique section, (b) Wall with pores, and coated with crystals of 

 quartz, (c) Thickened portion of wall with canals, {d) Laminae and pillars. 



stomachs and prehensile tentacles (Hydroids) which 

 form some of the simpler corals (Millepores, etc.), 

 and the crusts (Hydractiniae) which cover dead 

 shells and other bodies in the sea. When examined 



