128 



MOLLUSCA. 



Atrypa. 



Found in the Aymestry Limestone at Wallsgrove quarry ; 

 Sunny Hill Bank, Ludlow ; and also in the Upper Ludlow 

 Rock, Fownhope ; and Dog Hill, Ledbury. 



2. Atrypa affinis — The Allied Atrypa, pi. LIV.* fig. 

 1,2. 



Atrypa affinis. Sowerby, Sil. Syst. p. 610 and 614, pi. 6, 

 fig. 5. Atrypa reticularis, Dalman, Act. Holm. 1827, p. 127, 

 pi. 4, fig. 2. Hisinger, Pet. Suec. p. 75, pi. 21, fig. 11. Tere- 

 bratula affinis, Sowerby, Min. Conch. IV. p. 24, pi. 324, 

 fig. 2. Terehratula priscus. Von Buch, p. 71. Schl. pi. 17, 



fig. 2. 



Orbicular, with strong, deep, regular, radiatmg stria; ; upper 

 valve gibbous, with an obtuse, elevated sinus in front, filled at 

 the base with the longer-shaped sinus of the opposite valve ; 

 lower valve nearly flat. 



Found in the Carboniferous Limestone at Horncastle ; the 

 Melvern Hills; very common in the Upper Silurian Rocks; 

 occurs in the Aymestry Limestone at Ludlow and Aymestry, 

 and many other places; and in the Wenlock Limestone at May 

 Hill, Eastnor Park ; Abberley Lodge ; and Malvern Hills. 



3. Atrypa aspera. — The Rough Atrypa, pi. LIV. fig. 



49, 50. 



Atrypa aspera. Dalman, 1. c. p. 128, pi. 4, fig. 3. Hist. 

 Pet. Suec. p. 75, pi. 21, fig. 12. Sowerby, Sil. Syst. p. 623, pi. 

 12, fig. 5. Terehratula asper, Schloth, Nat. Pet. 1822, p. 68, 

 pi. 18° fig. 3. 



Orbicular; valves equally convex; with the base slightly 

 truncated; surface covered by numerous, radiating furrows, 

 increasino' in number by intermediate ones as they approach 

 the margins, these are crossed by undulating laminae. Diame- 

 ter half an inch. 



Very closely allied to A. affinis, but distinguished from it by the valves 

 being equally convex, and their form being more orbicular. 



Found in the Wenlock Limestone, Wenlock Edge. 



4. Atrypa tenuistriata The Thin-striated Atrypa, pi. 



LIV. fig. 80. 



Atrypa tenuistriata. Sowerby, Sil. Sj'st. p. 623, pi. 12, fig. 

 3. Terehratula ohtusa, lb. Linn. Trans. XII. p. 516, pi. 28, 

 fig. 3, 4. 



Slightly ovate transversely, gibbose; beaks small, a little pro- 

 minent, considerably waved, bent, and close to each other; base 

 with a narrow protrusion ; surface with fine, longitudinal striae. 

 Diameter one inch and three-quarters. 



Nearly allied to A. oblata, but will be distinguished by the position of 

 the beaks. 



Wenlock Limestone, Dudley, Wenlock, Abberley, Aymestry; 

 May Hill and the Lye, near Stourbridge. 



5. Atrypa compressa The Compressed Atrypa, pi. 



LIV. fig. 44, 45. 



Atrypa compressa. Sowerby, Sil. Syst. p. 629, pi. 13, 

 fig. 5. 



Slightly transverse, ovate, somewhat compressed, smooth ; 

 base with a very slight indentation ; beaks small, and a little 

 produced ; sides rounded. Length five lines ; breadth six hnes. 



Wenlock Shale, Nash and Woodside, near Presteign. 



6. Atrypa linguifera. — The Tongue-shaped Atrypa, pi. 

 LIV. fig. 21, 22. 



Atrypa linguifera. Sowerby, Sil. Syst. p. 629, pi. 13, 

 fig. 8. 



Orbicular, nearly globular, very convex, smooth; beaks large, 

 unequal, that of the larger valve considerably produced ; base 

 elevated, tongue-shaped. Length seven lines ; depth of valves 

 united seven lines and a half. 



Wenlock Shale, Stumps Wood ; Delves Green ; and Valley 

 of Woolhope. 



7. Atrypa depressa. — The Depressed Atrypa, pi. LIV. 

 fig. 78, 79. 



Atrypa depressa. Sowerby, Sil. Syst. p. 629, pi. 13, fig. 6. 



Transversely obovafe, compressed, smooth; sides depressed; 

 base much elevated, the elevated portion square ; beaks une- 

 qual ; with three or four, nearly obsolete, longitudinal furrows 

 along the middle. Length four lines ; width five lines. 



Wenlock Shale, Delves Green and Stumps Wood. 



8. Atrypa rotunda The Rounded Atrypa, pi. LIV. 



fig. 64, 65. 



Atrypa rotunda. Sowerby, Sil. Syst. p. 629, pi. 13, fig. 1. 



Almost orbicular, very convex, and smooth ; base elevated ; 

 beaks small, equal ; surface with fine, longitudinal, obscure fur- 

 rows towards the base. Length seven lines ; width seven lines 

 and a half. 



Wenlock Shale, Escarpments of Wenlock Edge. 



9. Atrypa cassidea The Little-helmet Atrypa, pi. 



LIV. fig. 53. 



Atrypa cassidea. Dalman, pi. 5, fig. 5. Phillips, Pal. Fos. 

 p. 83, pi. 34, fig. 148, a, b, c. 



Oblong-ovate, ventricose, smooth; beak large; sides and base 

 rounded ; a few indistinct lines of growth on both valves. 



Devonian Limestone, South Devon and Newton. 



10. Atrypa cuboides The Slightly-cubular Atrypa, pi. 



LIV. fig. 4, 5. 



Atrypa cuhoides. Sowerby, Geo. Trans. V. 2nd series, pi. 

 56, fig. 24. Phillips, Pal. Fos. p. 84, pi. 34, fig. 150. 



Subglobose; base elevated, and very flat on the surface; 

 margin with a deep square sinus ; beak small, acute ; lower 

 valve small, almost flat, with a large, produced, square append- 

 age, filling the sinus in the upper one; surface with numerous, 

 narrow ribs, emanating from the beaks, with about fifteen on 

 the mesial sinus, more elevated than the others, those on the 

 sides greatly curved, and on the base parallel. 



Devonian Limestone, Plymouth ; and Hope, near Torquay. 



11. Atrypa expansa. — The Expanded Atrypa, pi. LIV. 

 fig. 70, 71, and pi. LII. fig. 5, Spirifer expansa. 



Atrypa expansa, Sowerby, Min. Conch. VII. p. 14, pi. 617, 

 fig. 1. Spirifera expansa, Phillips, Geo. York. 



Transversely subovate, somewhat inflated; base nearly 

 straight ; destitute of a mesial fold ; surface covered with 

 broad, striated, imbricated fringes ; beak small, produced, and 

 incurved. 



When this species is deprived of its fringes, it presents the appearance 

 and answers to the description which I have given of it, p. 112, pi. LII. 

 fig. 5, under the name of Spirifer expansa. It is distinguished from A. 

 fimbriata by its even and inflated surface. 



Mountain Limestone, Bolland. 



12. Atrypa planosulcata. — The Flat-furrowed Atrypa, 

 pi. LIV. fig. 81, 82, and pi. LII. fig. 4. 



Atrypa planosulcata. Sowerby, Min. Conch. VII. p. 13, pi. 

 617, fig. 2. Spirifera planosulcata, Phillips, Geo. York. II. p. 

 220, pi. 10, fig. 15. See also p. 1 12. 



