Bulletin 26 90 



only sixteen ambulacral tubercles whereas 5. mexicana has twenty. 

 The apical system is similar to that of S. mexicana, and has the 

 right anterior genital plate incised in about the same manner. 

 In the specimens studied, there are no ridges on the plates of the 

 apical apparatus, but they were possibly eroded away although 

 the specimen appears well preserved. 



Salenia volana resembles 5. prestensis Desor, but it has only 

 five interambulacral plates whereas the European species has 

 seven. The distribution of the granules is also different. Its 

 general outline resembles that of S. prestensis more than that of 

 5. mexicana. Considering the few important differences already 

 mentioned, and the fact that 5. volana occurs in the upper Ceno- 

 manian, whereas S. prestensis is from the Aptian and S. mexicana 

 is from the Vraconian, it seems safe to regard it as a distinct 

 species. 



Since the above description was written, Dr. Bose has examin- 

 ed the type, and he believes that it is not the same as S. mexicana 

 Schluter. 



Number of specimens: 6. 



Occurrence: Lower division* of the Buda Limestone Shoal 

 Creek, Austin; and Manchaca, Texas. 



HEMICIDARIDM 



Genus Goniopygus, Agassiz 



Goniopygus budaensis, n. sp. 



Plate II, figures 1-8 



Dimensions. — Diameter at ambitus, 4.5 mm.; height, 2.25 

 mm.; apical disk, 3 mm.; peristome. 2.75 mm. 



Description. — Test of small size, subconoidal; abactinal 

 surface elevated; actinal surface flattened or concave. 



The ambulacral areas gradually widen from the apical disk 

 to the ambitus whence they decrease in width to the peristome. 

 They are composed of 6-7 plates surmounted by mammillated, 

 noncrenulated, imperforate tubercles which increase in size 

 from the apical system to the ambitus, decreasing again toward 

 the peristome. The pores are round, uniserial, and oblique. 



*In the vicinity of Austin the Buda Limestone displays two distinct phases : 

 a lower, chalky or marly, soft, white rock, and an upper, hard, yellowish to 

 reddish rock. 



