378 Methods of Collecting Minute Mollusca. 



dredge, taking out much more of the coarser material. A 

 casual examination of this revealed several A. iineata and odd. 

 specimens of other species. 



This decided me to gather a further quantity of mouldy 

 etc., which I treated in like manner, and packed this dried 

 stuff a\j'ay for minute examination at leisure. 



Later, I again passed all the material through a fine sieve 

 of miller's gauge, and reduced all the refuse to the capacity 

 of o>ie pint of fine dry dust, the same quantity of residue from 

 which Mr. R. Standen obtained his 44^) specimens. The two 

 bags of material, before sifting, would not at the most measure 

 more than two gallons. 



I then began a thorough and systematic search with a 

 powerful lens of large field ; the result to me was somewhat 

 astonishing, for the total number of shells discovered in the 

 small amount of material runs into four figures, A'iz., 1,031, 

 comprising 16 species. 



When it is remembered that this great quantity of shells 

 was collected from a small area of about four square feet, 

 and as I did not go deeper than three inches after removing the 

 loose top layer of leaves, altogether the quantity removed for 

 sifting and examination would not be more than one cubic foot. 



It seems almost incredible that such a vast quantity of 

 mollusca could be found inhabiting such a restricted space. 



A simple calculation on the above basis works out at 

 27,810 to the cubic yard, truly a marvellous example of the 

 prodigious numbers of small mollusca which lie hidden just 

 below the surface. 



I do not wish to infer that shells are to be found in such 

 great numbers everywhere in woods, not even in Eggerslack 

 Wood, which is so rich in small species of mollusca, but that na 

 doubt in suitable localities the minuter forms of snails may be 

 said to fairly swarm. 



It is no wonder then, that if this great prodigality of 

 molluscan life obtains, that the fallen leaves rapidly become 

 disintegrated and disappear, as without doubt these minute 

 forms of life feed on decomposing vegetation, and therefore 

 they hold an extremely important position in the economy of 

 nature, acting as very efficient and useful scavangers. 



The following table gives the number and percentage of 

 each species found: — 



Species Number. Percentage. 



Carychium minimum ... ... ... 827 80-2 



Acanthinula lamellata ... ... ... 48 4*6 



Punctum pygni(eum ... ... ... ... 43 4*1 



*Aciciila Iineata ... ... ... ... 40 3-8 



Small and immature Vitreas ... ... 30 2-9 



* Of this species 11 of the 40 (27-5 per cent.) were variety alba. 



Naturalist, 



