FOUND NEAR MACCLESFIELD. 63 



On comparing the present list with that of the Caernar- 

 vonshire deposit on Moel Tryfaen^ as the most elevated of 

 known drift fossils^ we have as yet found out of 60 species 

 only 32 at Macclesfield^ the excess of the Welsh list con- 

 sisting of arctic forms. The 18 which occur in the present 

 series, and not on Moel Tryfaen,, consist of the 7 southern 

 shells and 1 1 others which are all of British rather than 

 arctic distribution. 



The Macclesfield series is, therefore, distinguished from 

 that of Moel Tryfaen by the absence of the northern, and 

 presence of the southern shells. 



Comparing the present list with a list of shells found in 

 an estuarine deposit at Kelsey Hill, near Hull, somewhat 

 ftdler than that given by Mr. Prestwich (Greol. Journal, 

 xvii. 443), we find 24 common to the two, and all the 

 northern and all the southern absent from the Hull list. 

 The remaining absentees are all species of shells now com- 

 mon in British seas, whose non- occurrence in that bed is 

 not without explanation in the greater limitation of the 

 series and the position of the deposit near the great river 

 that supplied it with its Elephants^ teeth and its Cyrena 

 fluminalis. 



This latter comparison, however, is interesting in that 

 it afibrds evidence that the Cheshire beds were deposited 

 in a sea that beat fi'om the westward against the Derby- 

 shire Hills after the period had commenced during which 

 the physical conditions of the western sea have differed as 

 they now do from those of the eastern. On the other hand, 

 the presence of the three shells I have referred to (C cMone, 



rior lateral tooth, ligamental creTice, and a portion of adjacent surface, the 

 others very characteristic fragments from the central and jnarginal regions 

 of the valve. C. aculeatum, two fragments. These present, however, an 

 appearance very similar to certain deeper-water forms of C. echinatum, and 

 may be of that species. They diifer, however, ' in the direction of C. acu- 

 leatum from the fragments of C. echinatum occurring along with them. Area 

 lactea, two almost perfect valves, apparently genuine. 



