NATURAL SCIENCES OF PHILADELPHIA. 



213 



Marginals low, wide, the broad reflection equalling the base of 

 attachment and irregularly denticulated, as in Pupa. 



There are two European species of this subgenus, H. aculeata 

 and lamellata, whose jaw is described by Lehmann as rather 

 striated than ribbed. Their lingual dentition presents no sub- 

 generic differences from that of harpa, though the cusps of the 

 centrals are described as simply conical. 



Fig. 55. 



Jaw of Helix pidchella. [Morse ] 



Subgenus Vallonia. 



Jaw low, wide, slightly arcuate, ends but little attenuated, 

 blunt ; cutting margin without median projection ; anterior sur- 

 face with numerous crowded, broad 

 ribs, denticulating the lower margin. 

 (Fig. 55.) 



Lingual membrane (pi. XYIII., fig. 

 6) long and narrow. Morse gives Y3 

 rows of 11 — 1 — 1 1 teeth, with 3 perfect 

 laterals. I counted 10 — 1 — 10, with 3 perfect laterals. Centrals 

 with the base of attachment long and narrow, expanded and 



notched at the outer lower 

 ^^' angles, narrowed above and 



reflected ; reflection very small, 

 tricuspid, all the cusps bearing 

 very short cutting jDoints, the 

 central one, as usual, longest. 

 Laterals with the base of at- 

 tachment twice as broad as in 

 the centrals, the inner lower angle suppressed, notched at the 

 outer angle, broadly reflected above ; reflection larger than in 

 the centrals, with one inner, long, slender cusp, reaching nearly 

 the lower edge of the base of attachment, its cutting point quite 

 reaching it, and one small outer side cusp, also bearing a distinct 

 cutting point. Marginals low, wide, the reflection equalling the 

 base of attachment and irregularly denticulated along its edge, 

 the inner cusp the longest and bifid. The dentition is quite that 

 of Pupa. 



The above description is drawn from a specimen from Maine. 

 The European form is figured by Moquin-Tandon with a median 

 projection to the cutting edge of its jaw. Lehmann also figures 



Liugual dentition of Helix pidchella. [Morse ] 



