66 



SYSTEMATIC ARRANGEMENT 



broad, the inner part of the upper edge slightly reflexed, entire ; 

 outer lateral teeth subulate, curved. 



Lingual membrane of Ampullaria from Pernambuco broad, brown. 



Fig. 36. — Ampullaria canaliculata. 



s. Siphon. 



o. Operculum. 



Teeth 3 ■ 1 • 3 ; central broad, with seven teeth ; the central larger, 

 broad triangular or lance-shaped ; lateral conical, smaller, outer 

 smallest ; inner lateral oblong trigonal, with a reflexed front edge, 

 entire ; two outer lateral compressed, subulate, curved, acute at 

 the tip. 



Fig. 37. — Teeth of Ampullaria. 



The animals of Ampullaria scalaris, A. canaliculata, and .4. insula- 

 rum have a very long exserted tapering siphon from the left side of the 

 mantle, with a groove along its upper edge ; A. Roissii and A. zonata 

 a shorter truncated one, with a groove along its upper edge. Asolene 

 Plates is without any appearance of this part. Their siphons differ 

 from the siphon of the Zoophagous Mollusca in the edge being bent 

 up and not down, leaving the groove along its upper and not its 

 lower edge. 



The gills of Ampullaria are formed of a series of triangular laminse 

 placed in a line down the right side of the branchial cavity, close by 

 the side of the colon and ovarian tubes. A small mass of lamellae 

 on the outer left angle of the cavity ; the rest of the cavity filled 

 with a large fleshy bag open by a wide slit. Tentacles conical, elon- 

 gate. Eyes on short tubercles, separate from but close to the outer 

 base of the tentacles. Head short, the front of the side expanded 

 into short, conical, tentacle-like lips. Foot simple, folded across 



