EXISTING SPECIES OF SEA SHELLS ASSOCIATED WITH NORTHERN DRIFT. 533 



In the wide spread above described, these sea shells are accompanied throughout by 

 gravel and bowlders of northern origin ; and although, as before stated, the detritus is 

 much attenuated as it passes southwards into Worcestershire, some of the largest blocks 

 and in the greatest profusion, occur in the south-eastern extremity of Salop and adjacent 

 parts of Staffordshire, points very remote from the source of the detritus. 



The shells which I first collected were examined about two years ago by Dr. Beck, 

 and pronounced by him to be Buccinum reticulatum, and another species, Dentalium 

 Entalis, Littorina littorea, Tellina solidula, Cardium tuberculatum, Cyprina Islandica, Twr- 

 ritella Ungulina (Beck.), (T. Terebra, Auct.) with fragments of Venus, Astarte, Donax, 

 and other genera in too imperfect a state to be specifically recognised. 



These and all the other sea shells since collected in the range, with the exception of 

 two species detected near Worcester (including Turritella Ungulina, Cardium edule, Pur- 

 pura Lapillus, Area, and others), are recognised by Mr. J. Sowerby and all the conchologists 

 who have seen them to be identical with the species now inhabiting our coasts, and thus 

 no doubt is left as to the comparatively recent epoch when the tract in question was 

 submerged. Though very variable in their appearance, the accumulations containing 

 these shells indicate, that they have resulted from long-continued, ordinary, aqueous 

 action; and they present in general, much the aspect of great littoral deposits now 

 forming on shores, where the causes of change are of an active character 1 . 



The shells which have been found at Kempsey near Worcester are Turritella Ungulina 

 (Beck.), Purpura Lapillus (Lam.), Anomia Ephippium (Linn.), CyprceaPediculus (Gmel.), 

 Trochus cinerarius (Linn.), Murex Erinaceus (Gmel.), Ostrea edulis (Linn.), with Bulla 

 Ampulla (Linn.), and an Oliva*, 



» The distinguished Danish naturalist, Dr. Beck, to whom I have alluded, and who happened to be in 

 England when my memoir on this subject was read before the'Geological Society, informed me that all the 

 shells in question are equally found in the detritus which covers large tracts of his own country, which he 

 has no hesitation in considering an ancient bed of the sea, and in which also large bowlders have been mixed 

 up with smaller gravel and shingle. In this opinion he unites with Mr. Lyell, in showing a direct analogy 

 to the present bottom of the Cattegat and Baltic. Again, on the point of the resemblance of our drifted 

 English materials to shore deposits, I have the high authority of Mr. C. Darwin, who during five years constantly 

 observed the nature of such accumulations on the coast of South America, &c. Since his return, he has in- 

 vestigated the heaps of gravel and shingle around his native town (Shrewsbury), and he assures me, that they are 

 in no way to be distinguished from many shore deposits of the southern hemisphere. 



In some of the beds of sand near the surface (environs of Shrewsbury) Mr. C. Darwin has traced vertical 

 stalactitic cylinders, of the size of straws or less, filled with white friable calcareous matter, which he 

 conceives to have been made up from the decomposition of the shells. I have frequently seen such cylinders 

 in sandy loam though not often filled with calcareous matter, and I presume that they may have been formed 

 by some animal, and subsequently filled by decomposition of the overlying materials, aided by aqueous action, 



2 As some doubt might be entertained concerning the curious fact of this ancient collocation of species of 

 modern sea shells which now exist in very different latitudes only, I must state that both Mr. Strickland and my, 

 self, having narrowly sifted the evidence brought forward by Mr. Allies, are completely satisfied of its accuracy. 



The Oliva was dug out from the very bottom of the gravel pit in the presence of that gentleman and Mr. Peake 



3 x 



