630 



SHELLS OF THE WENLOCK SHALE. 



Atrypa aspera. (See PI. 12. f. 5.) Also Wenlock Limestone. 



Loc. Delves Green ; Hay Head ; Woolhope ; Stumps Wood. 

 Spirifer ? Pisum, f. 9. Lenticular, convex, indistinctly six-sided, smooth ; front even, truncated ; 



beaks equal, small j the area between them triangular, small. Length 3 lines, width the same. 



Loc. Hay Head. 

 Spirifer trapezoidalis. (See PI. 5. f. 14.) Also Ludlow Rock. 



Loc. Stumps Wood, and other places west side of Malvern Hills. 

 Spirifer radiatus. (See PI. 12. f. 6.) Also Wenlock Limestone. 



Loc. Woolhope ; Hay Head and Tame Bridge, Wallsall. 

 Spirifer crispus. (See PI. 12. f. 8.) Also Wenlock Limestone. 



Loc. Wallsall. 



Spirifer sinuatus, f. 10. (Terebratula sinuata, Sowerby in Linn. Trans, vol. xii. p. 516. t. 28. f. 5 and 6 ; 

 Delthyrls cardiospermiformis ; His. Anteckn. vol. iv. t. 7. f. 6 ; Dalm. I. c. p. 124. t. 3. f. 7 j His. 

 Pet. Suec. p. 74. t. 21. f. 9; Sp. cardiospermiformis ; Von Buch sur les Spirifers et Orthis, t. 1. 

 f. 7-) Obeordate, deeply two-lobed, eared, longitudinally striated ; larger valve very deep, with 

 an incurved beak ; area between the beaks triangular. Length 3± lines, width about the same, 

 often more. 



A drawing and description of this curious shell was sent to the Linnean Society in 1815, 

 under the name Ter. sinuata, and printed in 1818, it is therefore necessary to retain that specific 

 name. The length of the hinge line is liable to much variation ; in some cases it equals the 

 width of the shell. 

 Loc. Malvern ; Hay Head. 



Orthis hybrida, f. 11. Lenticular, most convex near the beaks, wider than long, radiated ; radii in- 

 creasing in number towards the margin ; front rather straight; valves equal; hinge line short. 

 Length 5|- lines, width 6 lines. 



In the short hinge line this species forms a link with the genus Atrypa ; but the narrow 

 area between the beaks and striated surface distinguished it as an Orthis. 

 Loc. Hay Head, Wallsall. 



Orthis filosa, f. 12. Semioval, very flat, finely radiated ; radii very numerous, unequal; hinge line 

 equal to or exceeding the length of the shell; sides rather straight; beaks scarcely elevated. 

 Length 10 lines. 



This is a delicate thin shell ; the radii resemble threads, stretched from the beaks to the margin. 

 Loc. Burrington ; and also at Oldcastle, Malvern. 

 Orthis canalis, f. 12a. (See PI. 20. f. 8.) Also in Caradoc Sandstone. Semioval, finely radiated; 

 radii more numerous near the margin ; larger valve very deep, w T ith a pointed incurved beak ; 

 the other concave along the middle, slightly convex along the sides ; front rather pointed and 

 gently depressed ; hinge line shorter than the width of the shell. Length 6£ Hues, width 

 about the same. 



This form resembles Orthis elegantula of Batman, but as it cannot be positively identified 

 we venture to give it a new name ; it is an extremely neat shell, with a hinge line shorter than 

 any of Dalman's figures. 



Loc. Delves Green; Croft ; Tame Bridge ; Woolhope (Falfield, near TortworthJ. 

 Orthis antiquata, f. 13. Semicircular, depressed, radiated ; radii deeply divided by distant lines of 

 growth ; principal radii few, with shorter intermediate ones near the margin ; lesser valve flat ; 

 dorsal area narrow, the full width of the shell. Length 6 lines, width about 8 lines. 



