﻿GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 



Ill 



genus, fossil or living. It is striking that this great size of the luiiule, 

 a progressive character, should be associated with small and shallow 

 ambiilacral notches "svhioh. for the genus, is a relatively primitive 

 character. 



The ambulacral petals arc beautifully distinct and well preserved 

 for part of their extent in the type and one other specimen. The 





V : 



Fig. 3. — a, Encope megatrema. IToi.otype, natuhal size. The akea showing part of 



AMBULACKUM II IS DKAWX FUOM A IRAGMENT. RESTORATIONS ARE INDICATED BT DOTTED 



LINES. 1), Section of t.iN'rrr.K to snow ttie inclined faces, drawn from two 



FRAGMENTS. 



posterior pair, I and Y, are long and narrow with a relatively wide 

 poriferous area and narrow median interporiferous area. The width 

 of the petal of ambulacrum Y is 11 mm. and its length is 50 mm. It 

 extends posteriorly in a wide curve around the lunule of interambu- 

 lacrum 5 and reaches a line coincident with the posterior end of the 



