EXPLANATION OF THE PLATES AND WOOD-CUTS. 



This fine shell was pubHshed (see Encyc. Metrop., loc. cit.) as a var. of A^. spi- 

 rata; but the size of the spire, the square form of the lower whorls, and its great 

 size, entitle it to the rank of a species. 



Loc. Mount Wise, Plymouth, where it occurs of all sizes. 

 Fig. 16. Pleurotomaria impendens. Conical, short, spirally striated, base concave; 

 whorls rather flat above, — the lower overhung by the angular base of the pre- 

 ceding whorl ; the stria? which encircle the whorls are less distinct towards the 

 upper margin. 



The imperfect specimens we possess of this shell will not allow us to draw up a 

 full description. 

 Loc. Plymouth. 

 Fig. 17. Pleurotomaria cirriformis ? (M. C. t. 171, f.2. Euomphalus delphinuloides ? 

 Auct.) An imperfect water-worn cast is all we possess of this shell ; the true P. 

 cirriformis is found at PafFrath, and has the above name applied to it by conti- 

 nental authors. 



Loc. Plymouth, also in the mountain-limestone. 

 Fig. 18. Turbo subangiilatus. Conical, elongated ; whorls about six, convex, marked 

 with three obscure spiral ridges on each ; aperture nearly circular. 



This which occurs with the last is in the same bad state of preservation. 

 Loc. Plymouth. 

 Figs. 19 and 20. Turbo cirriformis, Sower, (see Encyc. Metrop., loc. cit.) Conical, short, 

 oblique, smooth; apex obtuse; whorls slightly rounded, most prominent below; 

 aperture circular. Height and diameter equal, about i an inch. 

 An obscure, yet neat species, common at Stonehouse Hill. 

 Fig. 21. Murex Harpula (M. C. t. 578, f. 5.). Young individuals of this pretty species 

 are frequent in the Plymouth limestone. 

 Loc. Stonehouse Hill, also Bradley. 

 Fig. 22. TerebraHennahii, {Ter.Hennahiana,Sower.,seelE<ncyc.M.etTOTp.loc.cit.). Sub- 

 ulate, longitudinally and very finely striated, whorls slightly convex, striae gently 

 bent twice. Diameter not much above ^ of the height, which is but f ths of an 

 inch. 



Very like T. nexilis of the Petherwin beds (PI. LIV. f. 17.), but with still finer 

 and less bent striae, so that Rissoa Lefebvrei, T. nexilis, and the present species 

 will form a neat series of species characteristic of these beds. 

 Loc. Stonehouse Hill. 

 Fig. 23. Buccinum acutum (M. C. t. bOnQ, f. 1.). This is very imperfect, but cannot be 

 distinguished from the shell figured in Min. Conch., which is found in Queen's 

 County, Ireland. 



Loc. Stonehouse Hill. 

 Fig. 23 a. Buccinum imbricatum (M. C. t. 5QQ, f. 2.). Imperfect specimens, common 

 in this locality. 



Loc. Stonehouse Hill, also Bradley, near Newton Bushel. 

 Figs. 24 to 27. Buccinum spinosum (M. C. t. 566, f. 4.). These specimens are variously 

 distorted, but are all evidently referrible to this species, which we have seen also 



