Invertebrate Gallery of the Indian Museum. 113 



The sexes may be distinct, or may be united in the 

 same individual, as they are in the Land-snails. Repro- 

 duction takes place by means of eggs, which in the case of 

 many marine Moliusca are glued together in masses or 

 capsules of remarkable form. Several of the most peculiar 

 forms of these egg-caps ules are shown on the stand that 

 rises above the desk-cases, and among them a curious 

 form shaped like a ruff and much resembling a Sponge or 

 a Sea-mat in general fabric, 



Moliusca are found in all situations — on dry land at 

 all elevations, in swamps, rivers, lakes and ponds, on 

 the reefs and rocks of the sea-shore, at the surface of the 

 open seas, and in the deepest abysses of the ocean. 



The Molluscan phylum is divided by Professor Ray 

 Lankester, whose classification is here followed, into two 

 great branches, namely, (i) the Glossophora, in which there 

 is a distinct head provided with an odontophore ; and (2) the 

 Lipocephalay in which neither head nor odontophore are 

 present. 



I. 2. 3. MOLLUSCA GLOSSOPHORA. 



This branch includes three Classes, namely, (i) the 

 Gastropoda^ (2) the Scaphopoda, and (3) the Cephalopoda, 

 which are distinguished from one another chiefly by the 

 form of the foot. 



I. GLOSSOPHORA GASTROPODA. 



[Ciisiis l26Jl-168aC, ani) i-J13£]. 

 In the Gastropoda, of which the Garden Snail is an 

 example, the foot has usually a broad flattened sole-like 

 surface for progression. A shell is usually present, and 

 has the form of a cone, which may be simple, but more 

 commonly is coiled in a spiral — sometimes of many whorls. 

 The direction of the spiral is most usually from right to 

 left. The simple cone is seen in the Limpets [Patella), 

 Case 128: an elongated tube with an indefinite loose 

 spiral coil occurs in Siliquaria and Vermetus, Case 140X : 



