248 Systematic Paleontology 



angulated peripheries, followed by about 65 segments of nearly equal 

 size and rounded edges. 



This species is readily distinguished from the associated S. multi- 

 fasciatus by the globular form of the theca, the non-excavated base, the 

 smaller number of ambulacral branches, thus causing the surface to 

 appear smoother; finally, by the higher position of ^jlate 12, which does not 

 attain the basal row as in that species. 



Length of a large and regular theca 22 mm. ; transverse diameter 20-21 

 mm. Base not excavated. Plate 12 resting on plate 6 of the second circle. 



Occurrence. — HELDErvBERG Formation, Keyser Member. Devil's 

 Backbone, Maryland; Iveyser, West Virginia. 



Collection. — U. S. National Museum. 



Sph.^rocystites glocularis var. ovalis Schuchert 



Plate XXXVI, Fig. 2 



Sphwrocystites globularis ovalis Schuchert, 1904, Smith. Misc. Coi., vol. 

 xlvii, pt. ii, No. 1482, p. 253, pi. xxxviii, fig. 6. 



Description. — Associated with S. glohularis are specimens that attract 

 attention on account of their more elongate and regularly ovate thecse. 

 These specimens never attain the size of that species, however, and they 

 commonly retain a portion of the column, a feature much more rare than 

 in the variety oralis. In addition to the smaller size, and the rounded- 

 ovate outline of the theca, the variety is further distinguishable in always 

 having the 4 ambulacra less bifurcate. The number of branchlets varies 

 between 5 and 10, the average being 6 or 7. In 13 specimens, the ambu- 

 lacra divided as follows : 1 with 5 branchlets, 4 with 6, 4 with 7, 2 with 8, 

 1 with 9, and 1 with 10. In S. glohularis the average number of branch- 

 lets is between 10 and 12. 



Occurrence. — -Helderberg Formation, Keyser Member. Keyser, 

 West Virginia. 



Collection. — U. S. National Museum. 



