PAMLICO FOSSIL ECHINOIDS — BERRY 445 



posterior margin about one-half thickness of anterior and somewhat 

 sharper. Margin cut by five reentrant marginal ambulacral notches, 

 deep and narrow, which occasionally have been observed to make a 

 lunule (pi. 64, fig. 6). All the ambulacra are, except in the young, 

 deep narrow notches, but the posterior notches are the deepest. The 

 apical disk is central. The peristome is prominent and central and on 

 the aboral surfaces rises posterially to the greatest thickness of the 

 test about two-thirds of the distance from anterior margin and at 

 the anterior end of the lunule of the posterior interambulacrum 5, 

 and just above the periproct, which is confluent with the lunule. 

 The ambulacral petals are fairly narrow and the posterior ones are 

 longer than the others. The oral ambulacral furrows are deep and 

 branch toward the margin. The apical disk is well preserved, show- 

 ing the pores very distinctly. The entire surface is covered with 

 small tubercles, those on the oral surface most pronounced. 



In the young the marginal ambulacra notches are shallow, although 

 the potei'ior ones are more pronounced and the ambulacral furrows 

 are indistinct. Tubercles are present over entire surface; they are 

 more pronounced on the young ones. 



The fossil specimens range in size from 23 mm. long and 21 mm. 

 wide to 146 mm. long and 144 mm. wide, with maximum thickness 

 19 mm. 



For purposes of comparison I have figured a recent Encope inich- 

 ellni from Albatross station 2609, plate 63, figTires 2, 5, and 8, and a 

 series of fossil specimens ranging in size from 13 mm. long (pi. 65, 

 figs. 3, 6), to a large adult, 146 imn. long (pi. 64, figs. 1, 3). The 

 figured specimens are in the collection of the U. S. National Museum. 



I wish to express my thanks to Austin H. Clark, of the U. S. National 

 Museum, and to Dr. Robert T. Jackson, of Peterborough, N. H., for 

 advice and help in arriving at the identification of these fossils. 



J. S. SOVERNMENT PRINTING OFFICE: 19*1 



