75 
OBSERVATIONS ON THE BURROWING HABITS 
OF CERTAIN 
LAND AND FRESHWATER MOLLUSCS. 
W. EB. COLLINGE, 
Leeds; Honorary Librarian to the Conchological Society of 
Great Britain and Treland. 
ONE, perhaps, of the most interesting among the many peculiar 
habits of our Land and Freshwater Mollusca is that of burrowing. 
But few authors have troubled to inquire why and when molluscs 
burrow, so there is yet a wide field for patient and painstaking 
inquiry. 
In the summer of 1889 and in the January of 1890 I made a 
few notes upon the subject, which were communicated to ‘Science 
Gossip ’ in July 18go, in reply to a short paper upon the subject by 
Mr. Lionel E. Adams, B.A. Since then, whenever I have found 
either land or freshwater molluscs at any distance beneath the 
surface, I have carefully measured the depth, most of which will be 
found in the following observations. 
Some authors are of opinion that, with two or three exceptions 
(Zestacella, Achatina), molluscs burrow only when hybernating ; 
others, led by the observations of Mr. Lowe, consider that they also 
burrow when enlarging their shell. Undoubtedly, a number of the 
smaller species burrow when hybernating, but most of the larger 
land species do not, but generally congregate in large numbers under 
the eaves of out-houses, sheltered walls, holes in rocks, etc. My 
observations upon the mode in which molluscs enlarge their shells 
do not at all agree with those of Mr. Lowe. I have bred and 
reared C/ausilia rugosa and most of the commoner forms of /eé7x, 
ut I never saw them bury any part of their shell when enlarging it, 
nor can I see that it would be of any advantage to the animal; on 
the other hand, I am inclined to think that it would seriously interfere 
with the action of the mantle during deposition if the head was 
buried in the ground as stated by Mr. Lowe, and in many cases 
damage the membranaceous film before the calcareous portion was 
deposited. It is quite possible that they may increase their shells 
when in holes, ete. (burrows of earthworms). The following are 
the species I have observed, together with such other remarks made 
by authors as I have thought of interest. 
March 1891 
