JURASSIC PERIOD. 



437 



earliest known of the coin-shaped Rhizopods, called Nummulites and 

 Orbitolites, occur in Jurassic beds of Franconia, Germany. (A Ter- 

 tiary species is figured on p. 499.) Corals are of various kinds (Figs. 

 769, 770), and many have a modern look. Among Echinoderms, 

 there were Crinoids, mostly of the genera Pentacrinus and Apiocrinus, 

 a species of the latter of which {minus a part of its long stem) is 

 represented, reduced, in Fig. 771 ; also free Crinoids of the Comatula 

 type (Fig. 772), as well as many Star-fishes; also Echinoids (Figs. 

 773, 774), many with very stout spines, as in Fig. 774 a. 



Figs. 771-774. 



Echinoderms. — Fig. 771, Apiocrinus Roissyanus (xX), the middle part of the stem omitted; 

 772, Saccocoma pectinata: 773,Diademopsisseriale; 774,Cidaris Blumenbachii ; 774 a, spine of the 

 last. All Oolytic, excepting the last, which is Liassic. 



Among Mollusks, there was a great variety of new forms, many 

 peculiar to the Mesozoic era. The last of the Brachiopods of the 

 Spirifer and Leptcena families appeared in the Lias (Figs. 775-777). 

 These Leptcena were minute species (Fig. 776 a), contrasting won- 

 derfully with the abundant and large Leptcence of the Silurian, when 

 the family was at its maximum. The prevailing Brachiopods were of 

 the modern genera Terebratula and Rhynchonella. 



