206 



THE CARBONIFEROUS SYSTEM. 



and ferns were marine plants. Sj)irorhes multiply fast and grow very 

 rapidly ; and these little shells no doubt took immediate possession 

 of submerged vegetation, just as their modern allies cover fronds of 

 Laminaria and Fucus. 



As I have not met with a description of this little shell, I may state 

 that it is dextral, Avith two and a half to three turns. It is attached 

 throughout its length, and, when not compressed, presents a some- 

 what deep umbilicus. It is closely marked Avith beaded or unequal 

 transverse ridges. It has, when young, a close resemblance to Sp. 

 caperatus^ M'Coy, from the Carboniferous limestone of Ireland ; but 

 this species has only tAVO turns, and is sinistral. 



This shell has been described by Goeppert as a fungus, under the 

 name of Gyromyces ammonis. 



III. Crustacea. — It appears, in the table above, that as many as 

 fourteen beds of coal exhibit in their roofs shells of minute Entomos- 

 traca of the genera Cythere and Ba'irdla (Fig. 48),* and these occur 



Fig. 48. — Crusts of Entomostraca ; nat. size and magnified. 



(a) Bairdia ; (6) Cytherella inflata ; (c) Cythere. 



in such quantities that considerable beds of shale and bituminous 

 limestone are filled with their valves. Professor Jones regards the 

 species as marine or brackish- Avater ; and the same remark will, I 

 presume, apply to the crustacean Diplostylus Dawsoni, and a fragment 

 o{ Eurypterus described by Mr Salter from Coal-group No. 8 of Division 

 4 of the Section, as aa^cII as to a second and larger species from Port 

 Hood. Of the small Entomostracans there are several species, which 

 Professor Jones has now in his hands for determination. No Estherians 

 have yet been found in the Coal formation of Nova Scotia ; but I have 

 specimens of Leaia Leidyi from the LoAA'er Carboniferous of Plaister 

 Cove, and an undetermined Estheria from the same horizon at Horton 

 BlufiF. These will be described further on. 



* One at least of these is identical with a British Carboniferous species. 



