99 Bud a Limestone, Whitney 15 



same as that described above. In fact, the measurements agree 

 with the material here selected, but the species attains a much 

 larger size, e.g., length, 21 mm.; width, 19 mm.; height, 9.5 mm. 



Number of specimens: 27. 



Occurrence: Upper division of the Buda Limestone, Austin, 

 Texas. 



SPATANGIDM 



Genus Enallaster, d'Orbigny 



Enallaster traski, n. sp. 



Plate VIII, figures 1-3 



Dimensions. — Length, 40 mm.; width, 38 mm.; height, 20 

 mm. or more. 



Description. — Test of medium size, suboval, widest part 

 about midway of the length of the test; upper surface elevated, 

 rising abruptly from the anterior margin, possibly highest in 

 anterior, and gently sloping toward the posterior; anterior groove 

 broad and forming a deep, wide notch in the anterior margin; 

 posterior somewhat truncated; lower surface elevated in the 

 region of the plastron, depressed about the peristome, giving rise 

 to a keel-like form in the plastron. 



The unpaired ambulacrum is in the anterior groove The 

 pores consist of alternating elongate and rounded pore pairs. 

 In the specimens studied, this alternation is not regular, for 

 there are two pairs of elongate pores followed by a pair of round 

 pores ; then five pairs of elongate pores followed by a pair of round 

 ones, which are, in turn, followed by three elongate pore pairs 

 before another pair of round pores occurs. The area is not well 

 enough preserved to follow out the complete series. The anter- 

 ior paired ambulacral areas are flexuous. The pore zones are 

 composed of an anterior zone of rounded pores and a posterior 

 zone of round pores in the internal row and elongate pores in the 

 external row. Five pairs of the posterior zone correspond to 

 about seven pairs of the anterior zone. 



The posterior ambulacral areas are much shorter than the 

 others. Their pore zones consist of an anterior row of round 

 pores separated from a posterior row of elongate pairs. 



The surface of the test is covered with tubercles having broad 

 areolas bordered by fine granules. 



