116 University of Texas Bulletin 



DESCRIPTION Test: This species has nearly the form of Enallaster 

 bravoensis Bose, but differs in many respects, notably in having the pore 

 pairs of the unpaired ambulacrum all similar. Test low, elliptical in gen- 

 eral outline, notched at the anterior ambitus, rounded laterally, with three 

 distinct angulations, broadly truncate posteriorly. Anterior sulcus long, 

 apical system situated slightly more than two-thirds the length of the 

 mid-line from the notch of the anterior sulcus. Highest point of test on 

 the low posterior median carina about one-fifth the length of the test from 

 the posterior end. From this point the mid-line curves sharply poster- 

 iorly to the top of the truncated posterior end. This point is only slightly 

 taller than the edges of the anterior sulcus just in front of the apical 

 system. Slope of test forward from apical system gentle, almost a 

 straight line, similar to that of E. bravoensis Bose. The middle is the 

 most inflated point on the test. Inferiorly the most prominent point is 

 on the mid-line three-fourths the way back from the anterior end ; the shell 

 therefore is tallest at this point and anteriorly is wedge-shaped, as in 

 E. bravoensis Bose. There is an elevated median tuberculated area and 

 the peristome lies in a deep depression of the recurved anterior sulcus and 

 is bounded posteriorly by an overhanging pointed lip. Margins of shell 

 sharply rounded on approaching ambitus, and coarsely tuberculate. 

 Around each tubercle is a circlet of small tubercles, and the intervening 

 spaces recovered by- fine granules irregularly scattered. Oval projections 

 of postero-lateral ambulacra consisting of large smooth elongate plates 

 with scattered tubercles and fine granules. Laterally the test bears sev- 

 eral fascicle-like bands each consisting of three crowded rows of the 

 smallest sized granules. 



Anterior unpaired ambulacrum: Long, shallow, sides nearly straight, 

 making a rather shallow notch at the ambitus. Each pore zone has about 

 32 pairs of transverse slit-like pores, the pores of a pair being separated 

 by a conspicuously elevated, transversely elongate tubercle. The pores are 

 similar and the ten nearest the apical system show a graduation in size; 

 the others are approximately equal, except near the ambitus, where they 

 are more nearly circular. The pore pairs lie each on an elongate ambul- 

 acral plate which reaches the middle. Each plate has a double row of 

 small granules. 



Antero-lateral Ambulacra: Diverge at an angle of 180 degrees and 

 turn forward making over the central part of their course an angle of 

 about 47 degrees with each other. They then diverge and cross the am- 

 bitus far anteriorly. The anterior pore zone consists of about 22 pores 

 of minute, closely spaced, circular pores, situated for the most part about 



