other ones situate on the columella, approximate, extending 

 at right angles to the three preceding ones, the superior (infe- 

 rior ?) one oblique and smaller ; labrum reflected but not flat- 

 tened, bidentate, teeth lamelliform, prominent ; umbilicus 

 distinct. 



Length less than fa inch, breadth nearly ^ inch. 



The smallest teeth of the labium are sometimes obsolete." 

 (SAY, Journ. Acad. Nat. Sc. II. 375.) See also ADAMS, Cat- 

 alogue of Mollusca, in Thompson's Hist, of Vermont, and Sil- 

 Uman's Journ. XL. p. 271. 



An opportunity having been afforded for a careful examina- 

 tion of the authentic specimens of this species placed in the 

 Cabinet of the Academy of Natural Sciences at Philadelphia 

 by Mr. Say, and also of his Pupa modesta, the latter proves to 

 be merely a specimen of P. ovata, with the lip somewhat 

 fractured, by which the aperture has received a somewhat 

 modified form (fig. 8) ; and this circumstance has been the 

 source of no little embarrassment. Mr. Say's description is 

 as follows : 



P. modesta. " Shell suboval, minutely wrinkled ; apex 

 obtuse ; whorls six ; umbilicus distinct ; aperture obliquely 

 subovate ; labrum with a prominent, compressed, sernioval 

 tooth, equidistant from the extremities of the labrum, and a 

 somewhat conic one rather below the middle of the columella ; 

 labrum not inflected, joining the preceding whorl at its upper 

 extremity with a curve, bidentate, lower tooth placed opposite 

 to that of the middle of the labium, the other smaller and 

 placed a little above. Length 2 3 5 inch." (SAY, Long's Se- 

 cond Expedition, II. 260, pi. 15, fig. 5.) See also GOULD'S 

 Inverteb. of Massachusetts, 188, fig. 119. 



This species is constant in its external characters, but is 

 somewhat variable in its aperture. It is seldom that three 

 teeth are found on the transverse lip, the tooth on the left be- 

 ing almost always, and that on the right being frequently 

 wanting. Sometimes there is a minute tooth at the base of 

 the aperture, and sometimes a third tooth on the posterior 

 part of the outer lip. It is more ventricose than any other 

 2 



