Atrypae of the Central Missouri Devonian 47 
of the Callaway Limestone at Bellama Springs, Callaway Co., 
Mo., and the three species—Atrypa missouriensis Miller, Spirifer 
annae Swallow, and Athyris fultonensis Swallow are the charac- 
tertistic fossils of this zone at both localities?. 
ATRYPA PLANOSULCATA WEBSTER 
Plate 2, figs. 7—12. 
Atrypa hystrix planosulcata Webster, 1888. American Naturalist, 
Vol. 22, p. 1104. 
Atrypa planosulcata Webster, Fenton and Fenton, 1924. Michi- 
gan Univ. Cont. Museum Geol., Vol. 1, p. 139, pl. 27, figs. 13—16. 
Atrypa ‘planosulcata is comm@h in the lower third of the - 
Snyder Creek Shale—Strophonella‘ zone. It first appears in a 
thin, soft, brown layer directly above the basal Gomphoceras 
zone and continues upward for about thirty inches, at which 
Place most of the Brachiopods drop out to be succeeded by an 
abundance of Bryozoans and Corals. A careful study of a large 
series of this species, made during the summer of 1934, from+ 
both Central Missouri and Iowa localities show no differential 
characters, except in condition of preservation and the slightly 
smaller size of the Missouri shells. Swallow‘ identified the 
Missouri shells in 1864 as A. hystrix Hall. Greger® recorded 
it in a faunal list of the Central Missouri Devonian as A. hystrix 
occidentalis Hall, and Branson® figures it in his Missouri 
Devonian as A. spinosa Hall, from the Snyder Creek Shale, but 
fails to state that it occupies a very limited zone near the base 
of the formation. 
*Athyris ottervillensis Miller and Athyris brittsi Miller, are known 
to be immature specimens of Athyris fultonensis Swallow. Fully 
e and typical examples of Athyris fultonensis Swallow have 
been collected from the Otterville exposure. 
‘Swallow, Catalogue of the Boyce Collection, 1864. 
®Greger, Amer Jour. Sci., Vol. 27, p. 376, 1909. 
8Branson, Mo. Geol. Surv., Vol. 17, Series 2, p. 98, bl. 20, fig. & 
bl. 23, figs. 8, 9, oe Ce ee 
