GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 



Ill 



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

 a progressive character, should be associated with small and shallow 

 ambulacral notches which, for the genus, is a relatively primitive 

 character. 



The ambulacral petals are beautifully distinct and well preserved 

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



Pig. 3. — a, Encope megatrema. Holotype, natuhal size. The area showing part op 

 ambulacrum ii is drawn from a feagment. restorations are indicated by dotted 

 lines. 1), Section of lunule to show the inclined faces, drawn from two 



fragments. 



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

 poriferous area and narrow median interporiferous area. The width 

 of the petal of ambulacrum V 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 



