IOI BUDA IvIMESTONB, WHITNEY 1 7 



notches, to the peristome. 



The unpaired ambulacrum is situated in the anterior groove, 

 and is wider than the other areas. Each pore zone is composed 

 of eleven or more pairs of equal, rounded pores .followed by a 

 series of elongated, oblique pore pairs alternating with oval, 

 oblique pores. This sequence continues for about two-thirds 

 of the distance from the apical system to the ambitus. From this 

 point the pores are in simple, oblique pairs to the peristome. 

 The anterior paired ambulacra are not so long as the unpaired 

 one, but they are nearly as wide. They are slightly flexuous, 

 with the greatest curve at their posterior ends. The pores of 

 their anterior zones are small, round, grouped in pairs, and vari- 

 able in size. The posterior zone is much broader, and the pores 

 of each pair are unequal, the internal ones being oval whereas 

 the external pores are elongate. Seven pairs of the posterior 

 zone correspond to about five pairs of the anterior zone. At the 

 ends of the posterior zone, the pores become oval. 



The posterior ambulacral areas are short and relatively 

 broad. The pore zones are unequal, the anterior being narrower 

 than the posterior, and composed of pairs of rounded pores. 

 The pores of the posterior zone are elongate, the inner pores 

 being a little shorter than the outer ones. 



The tubercles are small, perforate, crenulate, and surrounded 

 by broad areolas bordered by fine granules. The tubercles are 

 largest in the interambulacral areas where they are associated 

 with several fasciole-like bands of very fine granules. On the 

 lower surface the tubercles are numerous, especially on the plastron. 



The peristome is small, oval, and situated very near the an- 

 terior. 



The periproct is rounded and situated in the upper part of 

 the posterior truncation. 



The apical system has four perforated genital plates, of which 

 the two posterior are more separated than the anterior ones. 

 Other details of the system are lacking' in the specimen studied. 



This species differs from E. texanus Roemer, in its form and 

 dimensions, the position of its highest point, and the ratio of 



