1* 



92 PROF. T. m'kenny hughes on the 



Mammaliferous Crag. Quart. Journ. Geol. Soc. vol. xxvi. 

 p. 92, vol. xxxvi. p. 515, vol. xxxviii. p. 681 ; Geol. Mag. 

 dec. 2, vol. i. p. 246, vol. v. p. 13. 

 Sorby. Proc. Geol. Polytech. Soc. West Hiding, Yorkshire, 

 vol. iii. 1858, p. 559, with the Eoraminifera named by Rupert 

 Jones. 



Gtnsnsr. Essay on Geol. Norfolk, White's Gazetteer, 1863. 



Tyndall, E. Geol. Mag. vol, i. p. 142 ; Proc. Geol. Soc. Yorksh. 

 vol. v. 1870, p. 7. 



Woodward, S. P. Geol. Mag. vol. i. 1864, pp. 49, 142, 216. 



Crosskey. Proc. Birm. Phil. Soc. vol. ii. p. 373. 



Simpson. Geol. "Nat. Hist. Repertory, vol. i. p. 57. 



Bedwell. Geol. Mag. dec. 2, vol. v. p. 517. 



Leckenby. Brit. Assoc. 1864. 



Gwyn Jeeereys. Brit. Assoc. 1874, p. 83. 



Dakyns. Geol. Mag. dec. 2, vol. vi. p. 238, vol. x. p. 93 ; Proc. 

 Geol. Soc. Yorksh. n. s. vol. vii. p. 123. 

 And the collections by Bean and others in the British Museum, and 

 the Leckenby collection in the Woodwardian Museum at Cambridge. 



In a note at the end of the list drawn up by Gwyn Jeffreys, and 

 published in Phillips's ' Geology of Yorkshire,' 3rd ed. p. 277, he says, 

 " All the above species are now living and inhabit the Arctic and 

 northern seas. Nucula Cobboldice is hitherto known from Japan 

 only." He further on makes the following important observations 

 on the admixture of littoral and deeper-water shells : — " I should be 

 inclined to reject from the list of Bridlington shells the following 

 species, viz. Mytilus edulis, Cardium edule, Littorina littorea, L. rudis, 

 and Purpura lapillus, because they are littoral, and therefore not 

 likely to be « associated with species which belong to the coralline 

 zone, such as Rhynchonella psittacea, Venus jluctuosa, Dentalium 

 striolatum, Admete viridula, and Columbella Holbolli " (= C. rosacea). 

 " These littoral shells may have come from an overlying or adjacent 

 bed, and become accidentally mixed with the shells from the deposit 

 under consideration." It is not uncommon to find on any shore 

 among the littoral shells others that have been torn away by currents 

 and tossed up by storms from far below low-water mark. But in 

 that case Gwyn Jeffreys evidently must have thought, from the 

 character of the deposit and other circumstances, that that explana- 

 tion was not sufficient. 



Mr. Lamplugh has worked this question out, and arrived at the 

 conclusion that some of the shell-bearing beds are transported by 

 the agency of ice from sea-bottoms of various depths further north 

 and mixed up with littoral and even freshwater deposits *. Whether 

 any of them have travelled far or not matters little for our present 

 purpose, as the condition must have been somewhat boreal on a shore 

 thus invaded by ice from arctic regions. I have therefore given the 

 list of the shells as a sample of what we should expect in a true 

 glacial deposit, without noticing the character of bed from which 

 it was derived. For such details I refer to Mr. Lamplugh's excellent 



* Geol. Mag. dec. 2, vol. vi. 1879, p. 393, 



