332 



TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Fig. 214. 



In the Southern and Southwestern States from North Carolina to Texas, 

 the species assumes often, not in all localities, the form de- 

 scribed as bucculenta. I repeat the description and figures of 

 the typical form, and a small variety from Alabama (Fig. 214). 

 This last often wants the parietal tooth : this form has same 

 jaw, lingual membrane, and genitalia as typical tJiyroides. 



Shell usually perforate, globose-conic, more or less elevated, 

 rather thin, shining, pale yellowish-green, surface regularly and 

 delicately furrowed by the stria? of growth ; whorls 5 or a little 

 more, rounded, and separated by a well-impressed suture ; base 

 convex ; aperture rounded ; peristome forming nearly two 

 thirds of a circle, rather broadly reflected, white, somewhat flesh-colored 

 behind, not completely covering a small umbilical perforation, sometimes en- 

 Fig. 215. 



M. bucculenta. 



M. bucculenta. 



tirely covering it ; parietal wall sometimes bears a small white tooth at the 

 middle, but of tener not. Greater diameter 18J, lesser 15J mill.; height, 10^ 

 mill. (Vol. III. PI. XI. a.) 



Mesodou clausa, SAY. 

 Vol. III. PI. IV., central figures. 



Shell subimperforate, conoidly semiglobose, rather solid, with crowded rib- 

 like strife, yellowish horn-color ; spire subregularly conoid ; whorls 5^, rather 

 convex, gradually increasing, the penultimate subangular, the last rounded, an- 

 teriorly subconstricted and briefly deflected ; umbilicus narrow, almost covered 

 by the reflected peristome ; aperture diagonal, subregularly lunate ; peristome 

 with a heavy, white thickening, uniformly subangularly reflected, its coltimel- 

 lar portion subdilated. Greater diameter 18^, lesser 16 mill.; height, 11^ 

 mill. 



Helix clausa, SAY, Journ. Phila. Acad., II. 154 (1821) ; American Conch. (1832), 

 No. 4, PI. XXXVII. Fig. 1; BINNEY'S ed., 17, PI. XXXVII. Fig. 1; ed. 

 CHENU, Bibl. Conch., III. 50, PI. XIII. Fig. 2. BINNEY, Bost. Journ. Nat. 

 Hist., I. 482, PI. XV. (1837) ; Terr. Moll., II. 107 (excl. syn.), PI. IV. (ex- 

 cepting the outline figures). DfiKAY, N. Y. Moll., 31, PI. III. Fig. 13 (1843). 

 -REEVE, Con. Icon., Fig. 694. BLAND, Ann. N. Y. Lye., VI. 336.- 

 PFEIFFER, Mon. Hel. Viv., IV. 321. W. G. BINNEY, Terr. Moll., IV. 46 ; 

 L. & Fr.-W. Sh., I. 149 (1869). 



Helix Pennsylvania*,, PFEIFFER, ex parte, Symb. ad. Hist. Hel., II. 36 ; Mon. 



