94 BRACHIOPODS. 



there is but little doubt that he had one of the commonest fos- 

 sils of the well-known locality just mentioned. Even if it 

 were desirable to overlook the name applied to the LaSalle 

 specimens, the more familiar specific title of Hall, A. subtilita, 

 could not be retained, inasmuch as the same form had pre- 

 viously been named and figured on at least two different occa- 

 sions. 



Swallow has described a number of shells under Spirigera 

 (Athyris) from the Coal Measures of Missouri and Kansas. 

 With most of these it is impossible to tell much from the diag- 

 noses given ; while with others it is manifest that the writer 

 had in hand various individuals of the very variable Athyris 

 argentea, so common everywhere in the Coal Measures of the 

 Mississippi basin. 



Nucleospira pisiformis HALL. 



Plate Ixi, fig. 5. 



Nucleospira pisiformis Hall, 1859: Pal. New York, vol. Ill, Explan. pi. 



xxviii B. 

 Nucleospira pisiformis Hall, 1882 : Geol. Sur. Indiana, llth Ann. Kept , p. 



301, pi. xxv, figs. 22-26. 



Shell subglobose, valves nearly equal. Ventral valve 

 slightly the more convex, especially toward the beak, which is 

 somewhat elevated ; area small, narrow. Surface nearly smooth, 

 but showing lines of growth, and the bases of hair-like spines. 



Horizon and localities. Upper Silurian, Niagara? lime- 

 stone : Gyrene (Pike county). 



Retzia? osagensis SWALLOW. 

 Retzia osagensis Swallow, 1860: Trans. St. Louis Acad. Sci., vol. 1, p. 653. 



Like R. vera, but much larger and with much finer costse. 

 Horizon and localities. Lower Carboniferous, Kinder- 

 hook beds : Cooper county ( Swallow ). 



