112 University of Texas Bulletin 



ENALLASTER WENOENSIS n. sp. 

 PL 5, figs. 3 



MEASUREMENTS : I 



(Type) 



Length 25.0 mm. 



Breadth 23.4 mm. 



Height 14.3 mm. 



Length from apical system to posterior border 9.0 mm. 



HORIZON : Upper five feet of Weno formation, marl facies. Base of 

 Weno: base of Pawpaw clay. 



LOCALITY : 720 (type locality) , one mile southeast of Riovista, Texas, 

 and one-half mile east of the Waco road ; 602, 618, near Fort Worth, Texas. 



DESCRIPTION TEST : Test oval in general outline, broadest point 

 anterior to the center, less elongate and more abruptly truncated poster- 

 iorly than H. riovistae n. sp. : anterior notch more pronounced than in 

 that species and anterior groove shorter. Apical system located a little 

 less than two-thirds the way back on the mid-line. The outline of the 

 test seen from above is ovate, with angulations ; the anterior corners of the 

 test are broadly round to the notch of the anterior sulcus, the posterior 

 corners on the ambitus are abruptly rounded to the excavated periproct 

 area. Oval surface inflated medially, the most prominent point being on 

 the mid-line about two-thirds the way from the anterior end of the test. 

 Aborally the highest point of the test is on the carina midway between the 

 posterior ends of the short postero-lateral ambulacra and the test slopes 

 gently anteriorly from this point, as in E. bravoensis Bose, and H. riovistae. 



Anterior unpaired ambulacrum sunk in the deep anterior sulcus which 

 is relatively shorter and narrower than that of H. riovistae n. sp. 



Each zone has about 31 pairs of ambulacral pores. About the first 

 twelve pore pairs are short, similar and equal except that they increase in 

 size from the apical system anteriorly. They have each two equal short 

 slits separated by a tubercle. Next come five pore pairs, three long and 

 two short, alternating. Next come two groups of two short pairs each, 

 alternating with long pairs. Thereafter anteriorly the pores are short and 

 similar. Throughout this series in all the short pairs, the pores of a 

 pair are separated by a tubercle, which in all the long pairs is lacking. 

 The type agrees with this description. The narrow ambulacral plates, 

 reaching the mid-line, have each two transverse rows of variable sized 

 tubercles, irregularly arranged. 



