No. of specimen. 

 I 

 2 



mm. 

 4.62 

 6.00 



3 



8.00 



4 



IO.OO 



5 



I2.00 



6 



IS.OO 



7 

 8 



17.OO 

 18.OO 



9 



24.OO 



95 Buda Limestone, Whitney ii 



wreath like system. The genital plates are pierced centrally 

 by large genital pores. The periproct is large and subpentagonal. 

 During its development this species undergoes considerable 

 change in form and proportions as well as in ornamentation, as 

 shown in the following table : 



Diam. Height Tubercles in Tubercles in 



mm. each half Amb. each half Iamb. 



2-50 1-1 3-3 



3.62 2-2 3-3 



4-75 2-2 4-5 



6.50 2-2 6-6 



2-2 6-7 



10.25 2 or 3-2 or 3 7-8 



13.00 2 or 3-2 or 3 7-8 



12.50 2 or 3-2 or 3 8-9 



17-5° 3-3 J " 11 



{Measurements, across the area at the ambitus) 



Number of specimens: 1 1 . 



Occurrence: Both divisions of the Buda Limestone, Austin 

 and Manchaca, Texas. 



PHYMOSOMA TIDJE 



Genus Cyphosoma, Agassiz 



Cyphosoma volanumf Cragin 

 Plate VI, figure 1 

 Cyphosoma volanum Cragin, 1893, Geol. Survey Texas Fourth Annual 



Report, p. 147. 

 Cyphosoma volanum Cragin, 1894, Colorado Coll. Studies, Vol. 4, pp. 45, 



47- 

 Cyphosoma volanum Hill, 1901, U. S. Geol. Survey Twent3^-nrst Annual 



Report, pt. 7, p. 283. 

 Cyphosoma volanum Clark, 19 15, U. S. Geol. Survey Monograph, Vol. 



LIV, p. 61, PI. XXI, figs. 2a-b, 3. 



Dimensions. — Diameter, 15 mm.; height, 6 mm. 



Description. — Test circular, depressed, slightly elevated 

 above the ambitus, concave below it. 



Ambulacral areas narrow, broadest at the ambitus, pointed 

 at the poles ; ornamented with two rows of alternating, mammil- 

 ated, crenluate, imperforate tubercles which are largest in the 

 ambital region. Areolas bordered by granules so arranged that 

 they form polygons with the largest granules at their angles; 



