344 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



of attachment, its cutting point quite reaching it, and one small outer side 

 cusp, also bearing a distinct cutting point. Marginals low, wide, the reflec- 

 tion 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 Euro- 

 pean form is figured by Moquin-Tandon with a median projection to the cut- 

 ting edge of its jaw. Lehmann also figures a wide, slight projection to the 

 cutting edge. A comparison of the description and figure of the dentition of 

 the European specimens given by Thomson and Lehmann shows no specific 

 difference. It will be noticed that Lehmann's figure of the centrals shows a 

 more developed reflection and cusp and no side cusps. I believe, however, that 

 careful comparison will show no variation in this or other particulars. 



Vallonia pulchella, MULLER. 

 Vol. III. PI. IX. Fis. 2. 



& 



Shell widely umbilicated, depressed, slightly convex above, thin and trans- 

 parent ; epidermis colorless ; whorls 4, very minutely striated, the last large, and 

 spreading at the aperture like a trumpet ; aperture orbicular, a little dilated ; 

 peristome much thickened, white, reflected, making nearly a continuous circle, 

 ends approaching ; umbilicus large, exhibiting all the volutions. Greater diam- 

 eter 3, lesser 2^ mill. ; height, 1 J mill. 



Helix piilchella, MULLER, Verm., 30. PFEIFFER, Mon. Hel. Viv., I. 365. BIN- 

 NET, Bost. Journ. Nat. Hist., III. 375, PI. IX. Fig. 2 (1840) ; Terr. Moll., II. 

 175, PI. XVII. Fig. 1. LEIDY, T. M. U. S., I. 256, PI. IX. Figs. 7-9 (1851), 

 anat. GOULD, Invertebrata, 176, Fig. 102 (1841), ed. 2, 429 (1870). ADAMS, 

 Vermont Mollusca, 159 (1842). W. G. BINNEY, L. & Fr.-W. Sh., I. 157 

 (1869). ' 



Helix minuta, SAY, Journ. Phil. Acad., I. 123 (1817) ; Nich. Encycl., ed. 3 

 (1819) ; BINNEY'S ed., 3. DEKAY, N. Y. Moll., 40, PI. III. Fig. 33 (1843). 

 -MOESE, Am. Nat., I. 544, Fig. 39 (1867). 



Helix costata, MULLER, vid. PFEIFFER, Mon. Hel. Viv., I. 366. 



Vallonia minuta, MORSE, Journ. Portl. Soc., I. 21, Figs. 54-56, PI. VIII. Fig. 

 57 (1864). TRYON, Am. Journ. Conch., III. 36 (1867). 



A circumpolar species, common to the three continents. From Canada East 

 to Nebraska and Florida in the Eastern Province, to New Mexico in the Cen- 

 tral Province, as well as in Nevada, Idaho, Arizona, and Colorado. For its 

 range in Europe and Asia see p. 343. 



The strongly ribbed variety ( V. costata) has been found in large numbers in 

 Kansas, and at Cincinnati and Philadelphia, and in Nevada. 



Jaw and lingual membrane described above. 



Genitalia figured by Lehmann (Lebenden Schnecken, PI. XI. Fig. 30). 



