FOSSIL CORALLINES. 



45 



sea-weed called Sargassuin are formed. In the 

 possession of the cups, perhaps filled with proto- 

 plasmic matter, called nematophores^ Professor AUman 

 thinks the Graptolites were nearly related to rhizopod 

 animals, and thus included characters now belonging 

 to two well-marked groups of marine animals. 



Fig. 33.— Double GraptoHte {pipiograj>tus ^nstis). 



All naturalists are agreed that the rod-bearing 

 Graptolites differed from the " sea-firs " in not being 

 fixed or rooted, as the latter always are. They were 

 therefore free, and no doubt gathered in great banks, as 

 appears from the usual way in which they are found 



