2 3 2 



HISTORICAL PALAEONTOLOGY. 



"slalked" Crinoids, the Jurassic rocks have yielded the re- 

 mains of the higher group of the " free " Crinoids, such as 





Fie 162 Pnttacrinus fascicnlosus, Lias. The left-hand figure shows a few of the 

 ioints of the column ; the middle figure shows the arms, and the summit of the column 

 with its side-arms; and the right-hand figure shows the articulating surface of one of the 

 column-joints. 



Saccosoma. These forms resemble the existing "Feather- 

 stars" (Comatitla) in being attached when young to some 



