1 6 Bulletin 26 100 



The peristome is small, transversely oval, and situated at 

 the end of the first quarter of the length of the test. 



The periproct is not preserved in the specimens studied. 



The apical system is composed of four genital plates with 

 large perforations, and five oculars. The right and left anterior 

 genital plates are the largest, and approximate each other in size. 

 The left anterior plate, however, unlike those of other species, 

 narrows at its posterior end and extends backward throughout 

 the entire apical system. 



This species resembles E. obUquatus Clark, but it is more 

 rounded in ambital outline and not so high. The anterior slope 

 is also much steeper than in that species. It is more rounded than 

 E. mexicanus Cotteau, and not so broad posteriorly. 



I take pleasure in naming this species in honor of Mr. P. D. 

 Trask, a student in Geology, whose interest and enthusiasm have 

 led to several important discoveries concerning the fauna of the 

 Buda Limestone. 



Number of specimens: 2. 



Occurrence: Buda Limestone, at base of upper division, Shoal 

 Creek, Austin, Texas. 



Enallaster bravoensis Bose 

 Plate VI, figures 3-5 



Enallaster bravoensis Bose, 1910, Institute* Geol. de Mexico, Boletin 25, 

 p. 168. 



Lam, 41 Figs. 5-10; Lam. 42, figs. 2-12; Lam. 43, figs. 1-2, 6-7. 



Dimensions. — Length, 38 mm.; width, 34 mm.; height, 

 21 mm. 



Description. — Test of medium size, cordate, broadest anteri- 

 orly, truncated posteriorly; upper surface arched, the greatest 

 elevation being between the apical system and the posterior 

 border; unpaired interambulacrum with a slight crest. Forward 

 from the apical system the test slopes rapidly; posteriorly, it 

 remains high and is truncated; lower surface flattened, depressed 

 about the peristome, and somewhat elevated posteriorly. The 

 anterior groove is broad and deep, commencing in the apical 

 system and extending forward around the ambitus, which it 



