PATULA. 165 



single subprominent tooth on the base of the shell ; peristome simple, acute, 

 its extremities separated widely. Greater diameter 8, lesser 1\ mill. ; height, 

 3 mill. 



Helix perspectives, SAY, Journ. Phila. Acad., I. 18 (1817) ; Nich. EncycL, IV. ed. 



3(1819); BINNEY'S ed. 9. BINNEY, Bost. Journ. Nat. Hist., III. 430, PI. 



XXI. Fig. 4(1840); Terr. Moll., II. 256, PI. XXX. Fig. 1. DEKAY, N. Y. 



Moll., 42, PI. III. Fig. 38 (1843). FERUSSAC, Tab. Syst., 44 ; Hist. Nat. des 



Moll., PI. LXXIX. Fig. 7. DESIIAYES in LAM., VIII. 130 ; 3d ed., III. 315 ; 



in FER., I. 81. CHEMNITZ, 2d ed., II. 114, Tab. LXXXV. Figs. 30-32; 



PFEIFFER, Mon. Hel. Viv., I. 103; III. 99 (excl. H. filiola). HEEVE, Con. 



Icon., 695. W. G. BINNEY, Terr. Moll., IV. 122. LEIDY, T. M. U. S., I. 



453, PI. VII. Figs. 4-7 (1851), anat. W. G. BINNEY, L. & Fr.-W. Sh., I. 



79, Fig. 139 (1869). 



Helix patula, DESHAYES, Encycl. Meth., II. 217 (1830). 

 Anguispira perspectives, TRYON, Am. Journ. Conch., II. 262 (1866). 



A Post-pleiocene species ; north of Maryland it is not now found east of the 

 Appalachian chain, but elsewhere is probably found over the whole of the 

 Eastern Province. 



Animal : head and eye- peduncles bluish-black; margin and posterior part of 

 foot white. Foot transparent, narrow, less in length than twice the diameter 

 of the shell, terminating acutely. 



The jaw and lingual membrane are quite like those of P. striatella. The 

 ends of the jaw, however, are more squarely truncated, and the striaj are not 

 converging. 



Lingual membrane (PI. IV. Fig. A) ; 15 1 15 teeth, 7 perfect laterals. 



The genitalia are figured by Leidy (Vol. I. PI. VII. Figs. 4 - 7). The same 

 general arrangement is found as in alternata, but all the organs are more elon- 

 gated ; the duct of the genital bladder is very long and thread-like. 



Patula striatella, ANTHONY. 

 Vol. III. PL XXX. Fig. 2. 



Shell umbilicated, orbicularly convex, thin, brownish horn-color, with crowded 

 ribs; whorls 4, scarcely convex, the last inflated below, rather wide; umbilicus 

 large, pervious ; aperture subcircular ; peristome simple, acute, its terminations 

 approached. Greater diameter 6, lesser 5| mill. ; height, 3 mill. 



Helix striatella, ANTHONY, Bost. Journ. Nat. Hist., III. 278, PI. III. Fig. 2 

 (1840). BINNEY, Bost. Journ. Nat. Hist, III. 432, PL XXI. Fig. 5 (1840); 

 Terr. Moll., II. 217, PL XXX. Fig. 2. GOULD, Invert. 178, Fig. 112 (1841). 

 -ADAMS, Vermont Mollusca, 162 (1842). DsKAY, N. Y. Moll., 43, PL III. 

 Fig. 40(1843). CHEMNITZ, 2d ed., II. 115, Tab. LXXXV. Figs. 36-33.- 

 PFEIFFER, Mon. Hel. Viv., I. 104. REEVE, Con. Icon., 727 (1853). W. G. 

 BINNEY, Terr. Moll., IV. 99. MOUSE, Amer. Nat., I. 545, Fig. 40 (1867). 



