Percij F, Kendall — Glacial Geology. 499 



The attempt to explain away the occurrence of southern forms by 

 such remarks as that Cyfherea chione is the only one of " anything 

 approaching a wide distribution," is in the first place hardly correct, 

 as Area lactea has been repeatedly found ; but, if it were, it is a very 

 damaging admission. Cytherea chione is most distinctly a southern 

 shell, and though it occurs in Carnarvon Bay I have heard of but 

 two examples being found, viz. : one dredged by Mr. MacAndrew, 

 many years ago, and the other, by myself, in a very " dead " con- 

 dition. The statement that " some Tertiary shells are now only 

 boreal in their habitat, notably Tellina calearea," and the footnote 

 quotation from Jeifreys, " Occurs in every Tertiary bed up to the 

 lied Crag," reveals one of the dangers to which the geologists of 

 the north-west are peculiarly liable. They are out of reach of any 

 Tertiary beds except the Pleistocene, and hence are compelled to 

 take some of their geology, when it relates to Tertiaries, as well as 

 their conchology, from Jeffreys. 



The only way in which Jeffreys' assertion could be made to 

 square with the facts is to turn the geological succession upside 

 down ; then, and then only, could one say that Tellina calcarea 

 occurs in every Tertiary bed tip to the Eed Crag. 



I say, without fear of contradiction, that it does not occur beloio 

 the Eed Crag, and that even its occurrence in that deposit is very 

 questionable. For my own part I do not admit the identity of 

 T. calcarea and the Eed Crag T. prelenuis. Furthermore, I assert, 

 and challenge refutation, that a large portion of the Tertiary Period, 

 to wit, the latter part of the Eed Crag and subsequent Tertiary 

 times, including the Chillesford and Forest Bed epochs, were 

 characterized by a climate distinctly " colder than the present." 

 Mr. Eeade holds a contrary view, but I am satisfied that he is 

 singular in his opinion. 



It remains now for me to notice the most remarkable of all the 

 shells of the Drift, viz., the extinct species. These have not received 

 the attention they deserve, as the temptation is so great to " locate " 

 a species as nearly as one can, instead of laboriously hunting out 

 its precise affinities. Strange to say, Edward Forbes in this way 

 overlooked the most remarkable shell in the Manx drift, viz., Nassa 

 reticosa, Sow. ( = iV. serrata, Broc), which he identified as " Buccinum 

 undatum var., resembling Nnssa reticosa." This shell is extremely 

 abundant in the Eed Crag, and less so in the Coralline, but, in East 

 Anglia, it does not appear to have survived the close of the Eed 

 Crag period. 



In the Manx Drift it is very abundant, and is associated with 

 Columhella sulcata, and Nassa monensis, Eed Crag species, and 

 Fusus Forhesii, a large and handsome species, which is not known 

 elsewhere either recent or fossil. A Mitra also occurs, which is 

 either extinct or a southern species. In the Wexford Drift N. reticosa 

 is found, together with 3Ielampus pyramidalis (otherwise confined 

 to the Pliocenes of East Anglia and Cornwall), a Mitra, and Turri- 

 tella triplicata, Broc. ( = r. incrassata, Sow.), a species very abundant 

 in British seas in the early part of the Pliocene period, but now 



