392 



PALAEOZOIC SYSTEM OF ROCKS. 



Among Brachiopods, the straight- hinged or square-shouldered kinds 

 continue, but pass out almost wholly with this age. 



Fig. 527, 



Fig. 529. 



Fig. 528. 



Figs. 523-529.— Echinoderms of the Carboniferous Age— Blastoids ; 523. Pentremites Burling- 

 toniensis (after Meek). 524. Pentremites gracilis (after Meek). 525. Fentremites cervinus (after 

 Hall). 526. Pentremites pyriformis (after Hall). 526a. Pentremite restored (after Lutken). 

 Crinids: 527. Batocrinus Chrystii (after Meek). 528. Scaphiocrinus scalaris (after Meek). 529. 

 Forbesiocrinus Wortheni (after Meek). 



Land and fresh-water shells, as might have been expected, are be- 

 ginning to be found in great abundance in the Coal-measures. The 

 genus Pupa, a land air-breathing gasteropod, and the genus Cyclas, a 

 fresh- water bivalve, and the genus Cypris, a little crustacean bivalve, 

 all of which are still represented by living species, are found. 



Of course, marine species, both Lamellibranchs and Gasteropods, 

 are abundant. Some figures of these are given below. 



Among Cephalopods, Orthoceratites still continue, but in diminished 

 number, variety, and size. Goniatites, introduced in the Devonian, 



