CAMBRIAN BRACHIOPODA— WALCOTT 99 



later, mature plicate stage of development of this section of the 

 Billingsellidce. 



Type. — Wimanella simplex, new species. 



It is to be noted that BiUingsella plicatella Walcott [1905a, p. 240] 

 includes some shells that are nearly smooth, and that B. highland- 

 ensis (Walcott) [1886, p. 119] is very finely costate. The former 

 species may be considered as being in part a form intermediate be- 

 tween BiUingsella coloradoensis (Shumard) [i860, p. 627] and 

 Wimanella harlanensis (Walcott) [1905c, p. 236]. I think, how- 

 ever, that the species with smooth shells should be grouped under a 

 generic head, as they indicate a marked phase in the evolution of the 

 forms formerly grouped under BiUingsella. 



The generic name is given in recognition of the valuable work of 

 Dr. Carl Wiman, of the University of Upsala, on the geology and 

 paleontology of the Baltic region. 



WIMANELLA ? INYOENSIS, new species 



Plate 10, Figure 4 



This species is represented by numerous specimens in the form of 

 casts in a calcareous sandstone. All of the shells are more or less 

 compressed and distorted. Some of those best preserved indicate 

 that the general outline was transverse. A specimen 6 mm. in 

 length has a width of 7 mm. 



The most striking feature is the presence of two strong radiating 

 ridges that originate near the beak and extend forward nearly to the 

 frontal margin. These ridges may be the casts of the main vascular 

 sinuses or it may be that they represent ridges on the exterior of the 

 shell, one on each side of the shallow median sinus. At present, 

 with the material before me, I am inclined to the view that they rep- 

 resent the casts of sinuses, and hence the provisional generic refer- 

 ence to IVimanella. 



N^othing is known with certainty of the outer surface or of the 

 substance of the shell. The interior casts and the matrices of the 

 casts show two strong radiating ridges, the shell substance having 

 apparently been removed and its place lost by the compression of the 

 sediment before its consolidation. 



Formation and Locality. — Lower Cambrian: Limestones in 

 Toll Gate Canyon, about 15 miles (24.14 km.) east of White Pine, 

 White Mountain Range, Inyo County, California. 

 4 — w 



