628 



SHELLS OF THE WENLOCK LIMESTONE. 



or most internal cone occupying the apex itself. Thus they form a pyramid of cups, or if viewed 

 in a reversed position, a series of broad rings gradually increasing in size, and capping but 

 not covering each other. Each cup or ring is thinnest at that part which is inclosed by the 

 succeeding ring, where also its diameter is least ; both surfaces are of a foliated structure, and 

 the outer blends with, and is lost in the external coat. Internally, each ring was apparently of 

 a cellular structure, for it is composed of depressed, imbricating, and regularly arranged grains 

 of calcareous spar. Some of the grains leave an impression upon the surface of each of the 

 steps, which is formed upon the cast of the cavity of the cone by the thick edges of the rings. 

 If these cells were the habitations of minute Polypes, they must have opened upon the edge of 

 the cup, and each succeeding generation must have been located around the parent stock, and 

 not upon or within the Polyparium, as in corals ; but there is no appearance of stellee or ra- 

 diating laminag. Upon the cast of the inner cavity may often be observed two, three, or more 

 longitudinal impressions, each composed of two nearly approximating, fine, sunken lines, pro- 

 duced by elevations where probably there were joinings in the cups. The cone of the larger 

 specimens is generally rather straight, with the rings regular, and no appearance of having been 

 attached to any other body; but the young specimens are irregularly curved, have more or less 

 distorted rings, and are fixed upon corals or shells. With such only does Schlotheim appear to 

 have been acquainted, and had not we been supplied with a complete series by Mr. B. Bright, 

 we should have been induced to consider the full-grown specimen as another species of the 

 same curious genus. 



Loc. Western slopes of the Malvern Hills ; Dudley. 



Tentaculites (Schloth.). Gen. Char. Shell subulate, tubular, open at one end; its outer surface 

 surrounded by rings ; aperture circular. [Schloth. Petr. p. 377.) 



Various opinions have been formed concerning the fossils comprised under this generic cha- 

 racter, some considering them to be the arms of Crinoidal animals and others the spines of a 

 Leptana (Recueil des Planches, 1831. PI. 6. f. 6, 12 and 13., Von Buch.). Their structure is lami- 

 nated and their shell thin. 



Tentaculites ornatus, f. 25. (Tent, annulatus? His. Pet. Suec. p. 113. t. xxxv. f. 2; Cyathocrinite& 

 pinnatus, in part, Goldfuss, Pet. vol. i. p. 190. t. lviii. f. 7 a.) Subulate, ornamented with large 

 rounded rings at irregular distances, the spaces between them filled with very small rings or 

 striae ; the interior even. Diameter 1 line, length 10 lines. Very frequent on the slabs of 

 limestone. 

 Loc. Dudley. 



Avicula reticulata ? Also Aymestry Limestone, (see PI. 7. f. 6.) 



Loc. Falfield, Tortworth. 

 My a ? Three very imperfect specimens, 



Loc, Falfield, Tortworth. 



SHELLS OF THE WENLOCK SHALE. 



PLATE XIII. 



Modiola antiqua, f. 1. Obliquely ovate, rather convex, smooth ; anterior lobe indistinct ; beaks small, 

 near the anterior extremity. Length 8 lines, width 4^ lines. 



