206 Mrs. McKenny Hughes—Pleistocene Mollusca. 
given in the list, nor can I find mention of it from similar gravels 
elsewhere. 
Mr. Gloyne in his paper on the Geographical Distribution of the 
Mollusca,' says, “‘ Helix aspersa attains a much larger size in Italy 
than in England. It is very difficult to believe that so abundant 
a British species has been introduced; but judging from the reduced 
size of English specimens, England would, to say the least, not 
appear to possess the most favourable climate for this mollusc.” 
Jeffreys says, ‘It does not appear to inhabit the north of Europe, 
nor Germany. . . but its range extends southwards through France 
to Sicily, as well as to Spain, Algeria, and the Azores.’ 
Tt occurs also in many widely separated parts of the world to 
which it is known to have been artificially introduced. As, for 
instance, Mauritius, 8. Australia, Valparaiso, Rio in Brazil, and 
sea-ports along the east coast of N. America. The only evidence we 
have bearing upon the time of its first appearance in Britain is its — 
plentiful occurrence in the Roman rubbish pits at Chesterford and 
elsewhere about Cambridge at such a depth and in such a manner 
as to preclude the possibility of its having got in subsequently.® 
Helix? pomatia, Linn., which lives now in the neighbourhood 
of Shelford, has not been found in any of these gravels, and I have 
never noticed it among the Roman remains of this district, even 
where shells of #. aspersa appear to have been thrown inin large 
quantities. 
Heliz (Arionta) arbustorum, Linn., is now found with Helix 
(Tachea) nemoralis in the Grantchester woods. It also lives under 
the willows close to the river, and is seldom found far from the 
water. A few days ago I noticed numbers of shells of this snail 
freshly broken by birds lying round the stones on which they had 
been smashed, all along the bank of the ditch near the bathing 
sheds on Coe Fen. ‘This species is extremely common in the gravels 
of Barnwell Abbey and Grantchester. It probably found a hiding- 
place as at present under willows, of which remains, as we have seen 
above, occurred so abundantly in one part of the pit at Barnwell 
Abbey. 
Cyclostoma elegans, Mill. I have found one specimen of this 
shell undoubtedly in the Mammalian gravel of Barrington. It does 
not now live in the immediate neighbourhood of Cambridge. I found 
quantities of dead shells, many with the opercula in place, several 
feet from the surface, in a tumulus of pre-Roman date, at Upper 
Hare Park, near Six Mile Bottom. 
It appears, therefore (see pp. 2083—204) that among the shells of 
the Cambridge gravels we have no fewer than 6 species which are 
no longer found in Britain. Several species which I have mentioned 
(see p. 205) have been found in the gravels, but have now disappeared 
from this district, though they occur in other parts of England, and 
some species which are common near Cambridge at the present time 
are absent from the gravels (see p. 205). 
1 Journ. Conch, vol. i. p. 289. 2 Brit. Conch. vol. i. p. 182. 
3 See also B. B. Woodward, Science Gossip, May, 1883, pp. 114, 237. 
