EOCENE ECHINODEKMATA. 153 



ambulacra wide, prominent, and covered with numerous small tubercles. Peristome in promi- 

 nent depression. 



Dimensions. — Length 56 millimeters; width 55 millimeters; height 34 millimeters. 



Description. — This relatively large, form has an elevated, gibbous upper surface and a nearly 

 flat lower surface except for the peristome depression. It is cordiform in marginal outline 

 about as wide as long and rounded laterally. 



The ambulacra are wide, the single anterior ambulacrum being situated in a deep groove, 

 which deeply indents the margin. The anterolateral paired ambulacra have long, broad sunken 

 petals, while those of the posterolateral pair are only about half as long. 



The interambulacral plates are covered with small perforated tubercles. The peripetalous and 

 lateral fascioles can be readdy traced. 



The peristome is in a pronounced depression near the anterior margin. The periproct is not 

 shown on the type form. 



Locality'. — Wilmington, X. C. 



Geologic horizon. — Castle Hayne limestone, upper Eocene or Ohgocene. 



Collection. — U. S. National Museum (1664S2). 



Linthea alabamexsis Clark, n. sp. 

 Plate LXXI, figures la-d, 2a-d. 



Determinative characters. — Test small, nearly round, except for groove on anterior margin and 

 slight truncation posteriorly, low, somewhat depressed, the upper surface sloping gradually 

 toward the apex. Ambulacra narrow, not deeply sunken, the posterolateral petals much shorter 

 than the anterolateral. Peristome near anterior margin. Periproct relatively high on narrow 

 truncated posterior margin. 



Dimensions. — Large specimen: Length 34 niilhmeters; width 35 millimeters; height 19 

 millimeters. Small specimen: Length 22 millimeters; width 22 mdhmeters; height 14 mdli- 

 meters. 



Description. — The test of this species is small, low, somewhat depressed, nearly round in 

 ambital outline, except for the rather shallow groove on the anterior margin and the shght, nar- 

 row truncation on the posterior margin. The upper surface slopes gradually from the anterior 

 margin posteriorly. 



The ambulacra are narrow and not deeply sunken. The single anterior ambulacrum is 

 situated in a narrow, rather shallow groove. The anterolateral paired ambulacra have long, 

 narrow, rather shallow petals, and the posterolateral pair are short and shallow. 



The interambulacral plates are covered with small perforate tubercles. The peripetalous 

 and lateral fascioles are not easily traced. 



The peristome is in a shallow depression near the anterior margin. The periproct is situated 

 relatively high on the narrow truncated posterior margin. 



Localities. — Prairie Creek, Wilcox County, Ala.; near Grand Glaise, Jackson County, Ark. 



Geologic horizon. — Midway group, lower Eocene. 



Collection.— U '. S. National Museum (166483, ljj§|371). 



Genus EUPATAGTTS Agassiz. 



Eupatagus carolinensis Clark, n. sp. 

 Plate LXXI, figures 3a-d, 4. 



Determinative characters. — Test medium size, oval, moderately tumid, nearly flat along the 

 median line, with shght keel. Ambulacra depressed, anterior very shghtly, paired ambulacra 

 in shallow grooves, long, the anterolateral pair shorter than the posterolateral. Interambulacra 

 shghtly tumid. Apical system excentric, well forward. Peristome excentric in front. 



Dimensions. — Length 4S millimeters; width 39 millimeters; height 22 millimeters. 



Description. — This very beautiful form has a test of moderate size, oval, moderately tumid 

 -on the upper surface and sloping up at a low angle along the median line toward the posterior 



