ECHINODERMA TA—CRINOIDEA . 



505 



18. D. cylindricus Billings. Ordovicic. 

 Calyx one fifth of an inch in diameter. Ventral sac as long as 



the arms. Plates all smooth. 

 Trenton of Quebec. 



19. D. latibrachiatus Billings. Ordovicic. 

 Calyx small (less than one third of an inch high), conical. Arms 



very broad, equalling at base the w^idth of the R. 

 Cincinnatian of Anticosti. 



20. D. cincinnatiensis Meek. (Fig. 1818.) 

 Height and w^idth of calyx about equal. 

 Cincinnatian of Ohio. 



21. D. caduceus Hall. (Fig. 18 19.) 



Ordovicic. 



Ordovicic. 



Height of calyx exceeding width. Surface marked by broad 



V^ 



Fig. i8i8. Dendrocrinus cincinna- FiG. 1819. Dendrocrinus caduceus, 

 tiensis, side view and stem joint enlarged, lateral view, natural size, and part of stem, 

 (After Meek.) X 2. (After Meek, Pal. Ohio.) 



and obscure ridges w^hich connect, leaving rhombic excavations 

 betv^reen. 



Cincinnatian of Ohio. 



22. D. casei Meek. Ordovicic. 



Height and breadth of calyx about equal (one third of an inch). 



