BRACHIOPODA. 245 



Remarks — Only one imperfect specimen occurs in the collection. In contrast with 

 the New York specimens it has a more broadly extended anterior margin, and more 

 acute cardinal angles. 



Horizon — Lower beds. 



Figured specimen No. 27503, Walker Museum. 



Superfamily Spiriferacea 



Family Atrypidae 



Genus Atrypa Dalman 



A try pa reticularis (Linne) 

 Plate 65, figure 2 



1767. Anomia reticularis Linne, Systema Naturae, ed. 12, tome i, p. 1132. 



1852. Atrypa reticularis Hall, Nat. Hist. N. Y. Pal., vol. 2, p. 72, pi. 23, fig. 8; pi. 270. 



pi. 55, fig. 5. 

 1913. Atrypa reticularis Maynard, Geol. Surv., Md. Low. Dev., p. 393, pi. 67, figs. 

 26-28. 



This very common Silurian and Devonian brachiopod has not been found in the 

 lower beds of the Little Saline limestone. It is represented in the upper beds by a few 

 imperfectly preserved brachial valves. The dimensions of the largest valve observed 

 are: Length 30 mm., width 29 mm. Other examples are considerably smaller. The 

 valves are moderately convex, and the surface is marked by radiating costae which in- 

 crease by intercalation. These are crossed by concentric lamellae, usually indistinctly 

 preserved, and giving the characteristic reticulated or decussated appearance. The 

 characters of the few specimens observed seem to be fairly constant. 



Horizon — Upper beds. 



Figured specimen No. 27502, Walker Museum. 



Family Spiriferidae 

 Genus Spirifer Sowerby 



Spirifer arenosus (Conrad) 

 Plate 65, figures 6-8 



1839. Dethyris arenosus Conrad, Third Ann. Rept. N. Y. Geol. Surv., p. 65. 



1859. Spirifer arenosus Hall, Nat. Hist. N. Y. Pal., vol. 3, p. 425, pi. 98, figs. 1-8; 



pi. 99, figs. 1-10; pi. c, figs. 1-8. 

 1908. Spirifer arenosus Clarke, Mem. N. Y. State Mus., vol. 9, pt. 1, p. 179, pi. 33, 



figs. 1-10. 

 1913. Spirifer arenosus Schuchert, Geol. Surv., Md. Low. Dev., p. 415, pi. 71, figs. 

 1-9; pi. 72, fig. 1. 



Description — Shell attaining large size, usually broader than long. The dimensions 

 of an average individual are: Length 50 mm., width 60 mm. Umbonal region wide, 

 beak considerably elevated above the hinge line; in the younger forms this elevation is 

 not so conspicuous. The cardinal extremities in the older individuals commonly well 

 rounded. 



Pedicle valve convex, with a wide shallow mesial sinus, which is almost obsolete, 

 in some specimens being little more than a flattening of the surface along that part of 

 the shell. At the apex it includes a single plication, which dichotomizes, until at the 

 anterior margin it is occupied by 5 or 6 plications. 



Brachial valve about equally convex with the pedicle. It is characterized by a 

 mesial fold, which presents a more prominent feature than the sinus. The fold starts as a 



