596 CAMBEIAN BRACHIOPODA. 



Several specimens of this shell have been collected by Prof. Theodore Groom, in honor of whom the specific name 

 is given. With no knowledge of its internal characters, the generic reference is necessarily provisional, but the species 

 approaches in outline and external characters some American forms of the genus 

 Oholella, especially the type species of the genus, 0. chromatica Billings, of the 

 Olenellus zone of Canada, from which, however, it appears to be separated by the 

 form of the beak and the shape of the umbonal region. 



There is little to add to Matley's description and observations, 

 except to call attention to the resemblance in general form and 

 surface of this species to the figure of Oholella crassa elongata on 

 A a' Plate LV, figure 5. As described and illustrated the species appears 



FiGUKE 62.— OdoZriia jroomj Matley. , i „ „ , „ /^x.„7„77„ 

 A, A', Top and side views of a ven- tO be a trUB OloUla. 



ftoi^MatleyIlM2%".\l7?flVlf^'^ FORMATION AND LOCALITY.— Lower Cambrian: (304c) « "Malvern quartzite" 



at Raggedstone Hill; and (304d)a "Malvern quartzite" at Midsummer Hill; both 

 [Groom, 1902, p. 94] in the Malvern Hills, between Herefordshire and Worcestershire, England. 



ObOLELLA ? LINDSTROMI Walcott. 



Plate LV, figures 4, 4a. 



Oholella lindstromi Walcott, 1901, Proc. U. S. Nat. Mus., vol. 23, pp. 674-675. (Characterized and discussed essen- 

 tially as below as a new species.) 



Tliis species differs from Oiolella mohergi Walcott in the more subacuminate outline of 

 the valves, the surface characters, and the interior of the dorsal valve. The last is well 

 shown by comparing figures 3e and 4a (PI. LV). Figures 3 and 4 clearly indicate the differ- 

 ence in surface of the two species. The surface of 0. ? lindstromi is much like that of Bicia 

 gemma (PL L, figs, la and Id). 



The ventral valve (PI. LV, fig. 4) occurs in a hard gray sandstone of the Mesonacis torelli 

 zone, and the cast of the dorsal valve (fig. 4a) is from one of the brown sandstone masses that 

 occur within the gray sandstone at Sularp. I am not sure that the dorsal valve illustrated 

 actually belongs to this species, as it is not associated with the typical ventral valve. It 

 differs from the typical dorsal valves of 0. mohergi in being more acuminate, and there is no 

 corresponding ventral valve associated with it in the material studied. 



I take pleasure in naming the species in honor of Dr. G. Lindstrom, to whom all paleon- 

 tologists are deeply indebted for liis many fine contributions to the paleontology of the Silurian 

 formations of Scandinavia. 



Formation and locai.ity. — Lower Cambrian: (321v) Gray sandstone of the Mesonacis torelli zone at Bjorkelunda, 

 south of Simrishamn, Province of Christianstad; and (321s) brown sandstone interbedded in gray-sandstone at Sularp, 

 near Lund, Province of Malmohus; both in Sweden. 



Obolella minor (Walcott). 



Plate LIV, figures 3, 3a-d. 



Camerella minor Walcott, 1890, Proc. U. S. Nat. Mus. for 1889, vol. 12, pp. 36-37. (Described and discussed as a 



new species.) 

 Camarellaf minor Walcott, 1891, Tenth Ann. Kept. U. S. Geol. Survey, p. 614, PL LXXII, figs. 4, 4a-d. (Text 



copied from preceding reference. Figs. 4, 4a-d are copied in this monograph, PL LIV, figs. 3b, 3, 3c, 3d, and 



3a, respectively.) 

 Camarella minor Walcott, Hall and Clarke, 1894, Nat. Hist. New York, Paleontology, vol. 8, pt. 2, p. 221. (Char- 

 acterized and discussed.) 

 Protorhyncha ? minor (Walcott), Schuchert, 1897, Bull. U. S. Geol. Survey No. 87, p. 334. (Generic reference changed 



and generic relations discussed.) 

 Oholella minor (Walcott), Clark and Mathews, 1906, Maryland Geol. Survey, vol. 6, 1906, pt. 1, p. 252, PL XVI, 



figs. 13 and 14. (No text reference. Figs. 13 and 14 are copied from Walcott, 1891a, PL LXXII, figs. 4a and 



4c, respectively.) 



General form ovate, biconvex. Surface smooth or marked by concentric lines and varices 

 of growth. Ventral valve subacuminate, moderately convex, with the most elevated portion 

 at the umbo, which curves downward toward the small apex; the posterior or umbonal third 



a Neither Groom [1902, p. 94] nor Matley [1902, p. 137] states wliich of these locaUties is the type locality. 



