RADULA OF PULMONATA 



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edges; central strong, tricuspid; laterals and marginals very 

 long, falciform, arched, unicuspid. 



Aurieulidae : Teeth very small ; central narrow, tricuspid on 

 rather a broad base ; laterals and marginals obscurely tricuspid 

 on a base like Succinea. 



Limnaeidae : Jaw composed of one upper and two lateral 

 pieces ; central and lateral teeth resembling those of Helicidae ; 

 marginals much pectinated and serriform (Fig. 141, A). In 



Fig. 141. —Portions of the radula of 

 A, Limnaea stagnalis L., with the 

 central tooth and two first laterals, 

 and two of the marginals, very 

 highly magnified; B, Ancylus 

 fluviatilis Miill., with two of the 

 marginals very highly magnified ; 

 C, Physa fontinalis L., with cen- 

 tral tooth and two of the marginals 

 very highly magnified. 



Ancylus proper the teeth are of a very different type, base 

 narrow, head rather blunt, with no sharp cusps, teeth similar 

 throughout, except that the marginals become somewhat pec- 

 tinated (Fig. 141, B) ; another type more resembles Limnaea. 



Physidae : Jaw simple, but with a fibrous growth at its 

 upper edge, which may represent an accessory plate ; radula 

 with very oblique rows, central tooth denticulate, laterals and 



