FOSSILS OF THE DEVONIAN. 145 
ties we place S. (ML) fimbriata Conrad, S. (M.) subundifera M. & W., S. (1) 
compacta Meek, and the Nevada shell under consideration. 
S. (M.) undifera and curvatus, var. undulata, Roemer, of the Middle De- 
yonian of England and the continent of Europe, S. (AZ) erubescens Kichwald 
(Leth. Ross, p. 703, taf. 34, fig. 18), S. (JZ) undifera, var. Takwanensis, 
Kayser, from the Devonian of China, and S. (M.) undifera Ethridge, from 
Queensland, all appear to belong to the same specific group and show 
its wide geographic distribution. 
It may be more convenient to use the older name S. (M.) fimbriata 
Conrad for the variety with the strong interrupted stri, as it occurs in the 
Lower Devonian of New York and the Upper Mississippi Valley region, 
and Roemer’s name S. (M.) undifera for the smoother, world-wide distrib- 
uted variety so, well illustrated by Davidson. If so, all the species men= 
tioned will fall under S. (/.) undifera with the exception of S. (M.) fimbriata. 
Professor Hall (Pal. N. Y., vol. iv, p. 216) calls attention to S. (JZ) 
setigera and S. (M.) pseudolineata as representing in the Carboniferous lime- 
stone the type of S. (JL) jfimbriata, and Mr. Davidson (Mon. Brit. Dev. 
Brach., p. 58) states that the resemblances between S. (AL) undifera and the 
Carboniferous S. (JL) ovalis and S. (AL) pinguis are often so striking as 
almost to lead one to believe that they are all mere modifications in shape 
of a single species. 
We have called attention in describing S. (1Z.) glaber, var. Nevadensis, to 
Prof. H.S. Williams’ life history of S. (IZ.) levis =glaber, where he traces its 
descent from certain Upper Silurian forms through S. (ML.) fimbriata, S. (MT) 
levis, S. (ML) pramatura, and considers S. (M.) pseudolineata as carrying on 
_ the type into the Carboniferous. This arrangement we have accepted, but 
the presence of the type of S. (JL) pseudolineata in the Lower Devonian 
suggests the view that the two types S. (M/.) undifera and S. glaber were 
already differentiated in early Devonian times, and that the line of descent 
of S. (ML) glaber and S (M.) pinguis and the group of species that each 
represent were determined in the Upper Silurian age. As we have no rep- 
resentations of the latter fauna in the West, further comparisons are omit- 
ted, the reader being referred to Professor Williams’ excellent paper for his 
views of the Silurian representations of the type of Spirifera under consid- 
eration (Ann. New York Acad. Sci., vol. ii, 1881). 
10c DW 
