PHYLUM MOLLtJSCA 



243 



collar is produced where the mantle joins the foot, and just beneath 

 this mantle-collar is the respiratory aperture ; back of the latter 

 is the anal opening. 



Internal Morphology 



Digestion. — Just within the mouth of a snail is a rounded organ 

 known as the buccal mass. The latter is composed of a ribbon of 



Fig. 135. — Arrangement of teeth in the radula of a snail. 



^Hermaphroditic Duct 

 / _,Orotesfis 



'' / ,'Semma/ Receptacle 



'//nfesfine 



Albumen Gland 

 / ^,Hearf 

 / /VasOeferens 



,Of/djcf 



'Dart Sac 



ytlcfcovs Gland 

 / / VoQina 

 / /Solvarv 0/ane/ 



/Penis 



/Crop 

 '' ^-Tentacle 



enilal Pore 



Anierior 



''Tentacle 



-Pharynx 

 'Mouth 



^\ ^Cerebral Ganglion 

 ^Sa/ifo. ry 



•.bra I Canal, 

 yry Qucr 



Fig. 136. — Internal anatomy of Helix. Shell removed. 



minute recurved teeth, the radula, supported and moved by con- 

 nective tissues and muscles. On the roof of the mouth is a horny 

 jaw which pulls food into the mouth cavity. It is then rasped by 

 the radula into fine particles and mixed with saliva which flows 

 into the buccal cavity from salivary glands that lie on each side of 



