Reviews — Dr. T. R. Holmes — Ancient Britain. 87 



contain more of the sylvan and moisture loving species. As a matter 

 of fact, the species taken as the type of the zone on account of its 

 greater prominence is not confined to that period, but is still living on 

 the spot, e.g. the gi'assy slope in the southern angle of Fistral Bay. 

 Some examples of this species from the zone have the thickened shell 

 so characteristic of those from Dog's Bay, Ireland. 



The forms that so far appear restricted to the zone are Vitrea 

 lucida, vrhich has not hitherto been recorded fossil, Pijramidula 

 rotundata^ Acantliinula aculeata, Helix hortensis, Clausilia laminata, 

 Carycliium minimtrm, and Pomatias elegans. Those found only in the 

 upper beds are Milax Soiverhyi, Helicella itala, and Helix coftpersa ; 

 while peculiar to the beds of doubtful age are Vitrina pellucida and 

 Jaminia cylindracea. 



The mode of occurrence and recurrence of the layers of Mytilus 

 shells calls for some further explanation than can at present be oif ered. 

 They occur at such defined intervals, and, if synchronous in the 

 several dunes, are spread over such a considerable area, that they 

 appear to mark epochs of some sort. The thicker patches and, of 

 course, the cooking sites indubitably speak of Man, but the persistent 

 thin upper seams, and especially the top one in each section, even if 

 those in the diiierent dunes do not correspond in time, seem to suggest 

 some other agency than Man needful to account for their being thus 

 evenly spread out. Do they, perchance, indicate periods of dearth of 

 other food during which crows and gulls were driven to subsist mainly 

 on mussels and carried them up on the dunes to devour? 



Another point of interest is the wonderful state of preservation of 

 the molluscan shells in the dunes, wherein they occur quite perfect 

 from the base right up to the turf, whereas when the slates come to 

 the top, save for a foot of soil, that soil never contains the trace of 

 a shell, though snails are living on the spot and must have done so for 

 ages. This is the case both on Towan Head itself and on East 

 Pentire Headland. The explanation seems to be that where the 

 drainage is uniform and perfect the percolation of rain-water has little, 

 if any, effect on the shells, whereas when there is no such complete 

 drainage the soil retains the moisture longer and the shells are 

 macerated and dissolved, just as thej'- are when the drainage is 

 diverted and concentrated in channels and pipes. 



E, E "ST" I E 'W S 



I. — Ancient Britain and the Invasions of Julius Caesar. By 



T. EicE Holmes, Hon. Litt. D. (Dublin). 8vo ; pp. xvi, 764, 



with 3 maps and 44 text-illustrations. Oxford : at the Clarendon 



Press, 1907. Price 21s. net. 



rnHE object of the present work is " to tell the story of man's life in 



X our island from the earliest times " ; and as the author has 



endeavoured "to treat it comprehensively from the beginning to 



the Eoman invasion of a.d. 43," it has a direct bearing on the later 



