154 MESOZOIC AND CENOZOIC ECHINODEBMATA OF THE UNITED STATES. 



ridge, which is low. The posterior margin is slightly contracted. The lower surface is nearly 

 flat, with a slight posterior keel. 



The ambulacra are broad, the anterior ambulacrum occupying a slight depression and the 

 paired ambulacra slight grooves in the petaloidal portions. The petals are long, the postero- 

 lateral being longer than the anterolateral. The pore pahs are rather large and connected by 

 furrows. 



The interambulacra are slightly tumid, the tubercles on the lower surface being much larger 

 than on the upper surface. 



The apical system is small and situated well forward. The peristome is large, semilunar 

 in shape, and excentric in front. The peripetalous fasciole is clearly defined. 



Locality. — Wilmington, N. C. 



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



Collection.— U . S. National Museum (164674, 166484). 



Genus BRISSOPSIS Agassiz. 



Beissopsis eimtjlattjs Ravenel. 



Brissopsis rimulatus Ravenel, 1S4S, Echinoidse, recent and fossil, of South Carolina, p. 4, PI. II, figs. 3 and 4. 

 Brissopsis rimulatus Ravenel, 1850, Am. Assoc. Adv. Sci. Proc, vol. 3, p. 160. 

 Brissopsis rimulatus Stefanini, 1911, Soc. geol. italiana Boll., vol. 30, p. 708. 



Description. — Ravenel did not describe this species in 1848 when he proposed the name, 

 but he published two very distinctive figures, which should be sufficient to identify the form if 

 material representing the species should be found. No such material was at hand when this 

 monograph was under preparation. 



Locality. — South Carolina (Ravenel). 



Geologic horizon. — Eocene (?). 



Collection. — Unknown. 



Genus MACBOPNETJSTES Agassiz. 



Macropneustes caeolinensis Clark, n. sp. 



Plate LXXI, figures 5a-d. 



Determinative characters. — Test small, elevated, tumid, subpentagonal. Apical system 

 excentric forward. Ambulacra narrow, petaloidal portions in narrow, shallow grooves. Surface 

 of plates covered with numerous tubercles. Peristome about one-third the distance from the 

 anterior to the posterior margin. 



Dimensions. — Length 28 millimeters; width 27 millimeters; height 22 millimeters. 



Description. — This attractive little form has an elevated test, tumid in form, and subpentag- 

 onal in ambital outline. The apex is excentric forward. The margin is rounded. The ambulacra 

 are narrow, the petaloidal portions being elongate in narrow, shallow grooves. The petals are 

 imperfectly closed. The surface of the plates is covered with numerous, irregularly dispersed 

 granules. The peristome is large, excentric, situated about one-third of the distance from the 

 anterior to the posterior margin ; irregularly dispersed tubercles. The interambulacra are slightly 

 gibbous above, the margin sharp, and the lower surface nearly flat. The fascioles are rather 

 indistinct. 



The peristome is large, semilunar, with large projecting posterior labrum. The periproct 

 is large and low on the imperfectly truncated posterior surface. 



Locality. — Wilmington, N. C. 



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



Collection. — U. S. National Museum (164651). 



