640 



HISTORICAL GEOLOGY. 



2. Actinozoans, Echinoderms. — The animal life was remarkable for tlie 

 abundance of a species of Lithostrotion, represented in Fig. 991, and for a 

 great profusion and diversity of Crinoids. This Lithostrotion is often colum- 

 nar in the external form of parts of masses (as shown in Fig. 991 a), although 

 essentially a massive coral. Among other Corals the old genera Zoplirevtis 

 and CyathophyUnm have their species, but not Favosites, Michelinia, Cysti- 

 phyllum, Dipliyphyllnm, Sarcinula, and others that were common in the De- 

 vonian. Species of Lithostrotion have been found in the Arctic lands 

 between Point Barrow and Kotzebue Sound. 



EoHiNODEEMS. — Fig. 992, Scaphioerinus Missouriensis ; 998, Actinocrinus proboscidialis ; 994, Dorycrinus 

 unicornis ; 995, Woodocrinus elegans ; 996, BatocrinusChristyi ; 997. Platycrinus Saffordi ; 998, ttie proboscis 

 of Batocrinus longirostris ; 999, Penti-emites pyriformis ; 1000, 1000 a, P. Godoci ; 1000 a, top view ; 1001, 

 portion of the shell of Archajocidaris Wortheni ; 1002, spine of A. Shumardiana (x 2) ; 1002 a, base of spine ; 

 1003, id. of A. Norwood!. Figs. 992-995, 997-1008, Hall ; 996, Swallow. 



The number of species of Crinoids described from the American Sub- 

 carboniferous limestone exceeds 650. Some of the forms are represented in 

 Figs. 992 to 1000, but mostly wanting the arms and stem, as is common with 

 these fragile species. Fig. 995 represents the perfect body of Woodocrinus 

 elegans, with the arms closed together, and, below, a few segments of the 

 pedicel, which, entire, may have been a foot long; 992 is a Scaphiocrinus, 

 with the arms broken. In Poteriocrinus Coxanus Worthen, the arms are six 

 inches long, and the breadth of the expanded Crinoid must have been nearly 



