392 Systematic Paleoktology 



Length 1.8 cm. ; width 2.4 cm. 



The writer was much surprised to find an example of this species from 

 the Upper Oriskany collected by Kowe from Shriver's Ridge, Cumberland. 

 Heretofore this species was not known to occur in America in strata older 

 than the Marcellus, but in South America the paleontologic evidence seems 

 to indicate an earlier occurrence. There is now proof that the ,=pecies 

 occurs as low as the Upper Oriskany and recently Prof. Williams ' has 

 recorded its presence in the Chemung fauna. It is therefore a fossil 

 characteristic of nearly the entire Devonian system. 



Occurrence. — Oriskany Formation, Eidgely Member. Shriver's 

 Ridge, Cumberland. 



Collection. — Maryland Geological Survey. 



Superfamily SPIRIFERACEA 

 Family ATRYPIDAE 



Genus ATRYPA Dalman 



Atrypa recticulaeis (Linne) " 



Plate LXVII, Figs. 26-28 



Anomia reticularis Linne, 1767, Systema Naturae, ed. xii, tome i, p. 1132. 

 Atrypa reticularis Hall, 1852, Nat. Hist. N. Y., Pal., vol. ii, p. 72, pi. xxiii, fig. 

 8; p. 270, pi. Iv, fig. 5. 



Description. — " Shell subrotund, more or less compressed, subtruncated 

 above or on the hinge-line ; valves more or less equal, the beak of the dorsal 

 valve extending beyond the ventral valve, and the latter being deeper and 

 more convex in older specimens ; surface marked by dichotomous rounded 

 striae, which are crossed by concentric elevated lamellae, giving a reticu- 

 lated or decussated character to the surface. It is impossible to give a 

 definite description of this very protean species, which commences its 

 existence in the Clinton group and continues with various modifications 



' Amer. Jour. Sci., vol. xlii, 1902, p. 429. 



= For figures of the Upper Silurian and Lower Devonian variation see Hall, 

 1859, Nat. Hist. N. Y., Pal., vol. iii, pi. xlii, figs. la-r. For a complete American 

 bibliography and synonymy see Schuchert, 1897, Bull. U. S. Geol. Survey, No. 

 87, pp. 154-155. 



