BRACHIOPODA. 239 



plications increase rapidly in size toward the anterior margin. Near the postero-lateral 

 margins the last two or three become obsolete. 



Remarks — The exteriors of the separate valves occur. This species differs from 

 Eatonia peculiaris Conrad, in its smaller size, in the presence of coarse angular plica- 

 tions, in the more broadly extended pedicle valve, and in the sharper mesial fold of the 

 brachial valve. 



Horizon — Lower beds. 



Holotype and Paratypes No. 27466 Walker Museum. 



Genus Uncinulus Bayle 



Uncinulus parvus sp. nov. 



Plate 63, figures 11-12. 



Description — Shell small, sub-pentagonal in outline, length and width nearly equal, 

 the postero-lateral margins meeting at the beak in an angle of 90 degrees or a little less. 

 The dimensions of a perfect specimen, the hologype, are: Length 17 mm., width 17.5 

 mm., the greatest width midway between the beak and anterior margin. Cardinal 

 extremities rounded. 



Pedicle valve moderately convex, the most pronounced convexity in the region 

 of the umbo; depressed anteriorly into a broad ill-defined sinus. Beak. small, acute, 

 elevated over the beak of the opposite valve. 



Brachial valve a little more convex than the pedicle, elevated anteriorly into a 

 scarcely perceptible mesial fold ; beak incurved below that of the other valve. 



Surface of each valve marked by about 18 simple, rounded plications, which become 

 obsolete in the umbonal region, 6 of them included in the fold and sinus. Fine con- 

 centric striae and irregular lines of growth cross the plications. Lateral and anteriors 

 margins of contact sharply serrated. 



Remarks — Only one entire specimen of the above species, the holotype, has come 

 under observation, but a separate pedicle valve is doubtfully referred to the same 

 species. The species has been observed only in^ the upper beds, and is distinct from 

 all the other Uncinulae present because of its small size, and the slight development 

 of the fold and sinus. For these reasons one cannot be reasonably sure that it is a mature 

 individual. The form resembles somewhat closely the figured specimen of Uncinulus 

 convexorus 1 Maynard, fig. 14, but is entirely dissimilar to figs. 9-13 of the same species 

 on which presumably the description is based. 



Horizon — Upper beds. 



Holotype No. 27463 Walker Museum. 



'Maynard, T. P., Geol. Surv., Md. Low. Der., pi. 65, figs. 9-14. 



Uncinulus salinesis sp. nov. 

 Plate 63, figures 8-10 



Description — Shell of medium size, sub-pentagonal in outline; width slightly greater 

 than the length. The dimensions of the holotype are: Length 32 mm., width 35 mm., 

 the maximum width anterior to the middle of the shell. The lateral margins conspicu- 

 ously flattened and sharply serrated. The postero-lateral margins slope abruptly to the 

 beaks, and are gently concave forming oval areas. 



Pedicle valve depressed convex in the umbonal region, gradually flattening out to 

 form a broad shallow sinus at the anterior margin, which projects in a linguiform ex- 

 tension, fitting into the mesial fold of the opposite valve. The surface slopes gradually 

 to the lateral margins, where it turns abruptly forming a sharp angle, and meeting the 

 brachial valve at right angles. Beak triangular, with acute apex, and apparently a 



