894 



PALAEOZOIC SYSTEM OF ROCKS. 

 b 



Jgk 



ftfli i it 



1 I . :li 





Fig. 536 



Fig. 538. 



Figs. 535-538. — Carboniferous Brachiopods: 535! Spirifer plenus (after Hall); a, dorsal view: b, 

 side view. 536. Chonetes Dalmaniana. 537. Productus punctatus (after Meek). 538. Produc- 

 tus mesialis (after Hall); a, ventral view; b, side view. 



duction here of Limuloids (king-crabs), Fig. 555, and of Macrourans 

 — long-tailed Crustaceans (lobsters, crawfish, shrimps, etc.), Figs. 557 

 and 559. Here, then, we have two important steps in the progress of 



Fig. 539. 



Fig. 542. 



Fig. 544. 



Figs. 539-544. — Carboniferous Land and Fresh-water Shells: 539. Pupa vetusta (after Daw- 

 son— a Land-Shell; a, natural size; b, enlarged. 540. Cypris (after Dawson); a, natural size. 

 541. Spirorbis (after Dawson); a, natural size. 542. Naiadites (after Dawson). 543. Dawson- 

 ella Meekii (after Bradley). 544. Anthracopupa Ohioensis (after Whitfield). 



