534 Systkjiatic Paleontology 



Bollia clarkei Ulrich, 1894, Geol. and Nat. Hist. Surv. Minnesota, Final Kept., 



vol. ill, pt. ii, p. 669. 

 Kladenella clarkei Ulrich and Bassler, 1908, Proc. U. S. Nat. Mus., vol. xxxv, 



p. 319. 



Description. — This well-marked species which wa.* originally described 

 from the Lower Helderberg of Herkimer County, New York, may be 

 readily distinguished from associated forms of Klcedenella by its less 

 elongate shape and more conspicuous sulci. 



Occurrence. — Helderbeeg Formation, Keysek Member. Cumber- 

 land. 



Collection. — U. S. National Museum. 



Klcedenella clarkei var. paupera Ulrich and Bassler 

 Plate XCVIII, Figs. 1-3 



Klcedenella clarkei paupera Ulrich and Bassler, 1908, Proc. U. S. Nat. Mus., 

 vol. xxxv, pi. xliii, fig. 5. 



Description. — The specimens referred to under the above name are 

 obviously close allies of Klcedenella clarkei (Jones). This species, to- 

 gether with K. halli constitutes a readily distinguishable group of the 

 genus in the sharp definition of the lobes and the unusual depth and 

 length of the sulci. The lobation of the valves ordinarily appears to con- 

 sist of four ridges joining ventrally. The typical form of the species is 

 a common fossil in the underlying Silurian fomiation. The variety here 

 figured is distinguishable by characters of only minor value. Its valves 

 and the ridges especially are thinner, giving the whole a somewhat emaci- 

 ated appearance. It is noted further that the furrows present somewhat 

 irregularly distributed papillae which have not been observed in the earlier 

 phases of the species. The figures on pi. ii afford a sufficiently accurate 

 representation of the species to render its recognition easy. 



Length .75 mm. ; height .45 mm. 



Occurrence. — Helderberg Formation, Keyser Member. Cumber- 

 land. 



Collection. — IT. S. Xalioiial ^[useum. 



