GEOLOGICAL EANGE 



257 



large dimensions ; there are, however, many others 

 in the Carboniferous series which, although smaller 

 in size, are often very numerous, and therefore 

 important as rock-builders. Many of these species, 

 and even genera, are more or less restricted to 

 the Carboniferous system. Among other Carboni- 

 ferous types we may mention the genera Hcvploplirag- 

 ■ni'nnn^ Stacheia, NodosijieUa, Endotliyra (generally a 



Fig. 29. — Fusulina Limestone ; Kussian Carboniferous. 

 X 60. Original. 



Carboniferous genus, but also found in the Trias), 

 Ammodiscus, Textulavid, VdhiiJ'nui^ Lagena, Arclice- 

 discus (restricted), and Fnsitliita (restricted to Car- 

 boniferous and Permian). 



The genera HaccainiiiiiKi (iig. 28) and Fusuliiia 

 (fig. 29) often form the larger proportion of extensive 

 beds of limestone, as we have already seen, but 

 occasionally some of the smaller types, as Endothyra 



s 



