184: PROCEEDINGS OF THE ACADEMY OF 



paululum iutrante, angulato conjunctis, dextro laminis duobus horizontalibiis, 

 Curtis, intus positis munito ; basali dentibus duobus perpendicularibus in 

 margine positis, uno parvulo, altero majore, munito. 



Diam. maj. 13, min. 11, alt. 5 mill. 



la Provincia Mexicana Cinaloa ad flumen Mazatlan collegit Gambel. Collect. 

 Pliillips. 



Var. minor diam. maj. 10, min 7, alt. 3. In Texas habitare dicitur. Collec. 

 Mea. 



Shell above depressed, shining, with hardly perceptible striae, whitish, suture 

 slio"htly impressed, whorls five, rather convex, last whorl rather proportionally 

 larger, with two pits behind the peristome, and channelled ; spire slightly 

 elevated ; below smooth and shining, one full ventricose whorl and a portion 

 of a second, which rapidly decreases in the slightly perforated umbilicus ; aper- 

 ture basin-shaped, much complicated by five teeth ; one on the parietal wall is 

 Avhite, heavy, angular, somewhat like that of H. Texasiana, connecting the 

 the two extremities of the sharp and reflected peristome. On the edge of the 

 peristome near the columella are two short, stout, perpendicular teeth, the 

 nearer one the shorter ; within the aperture are two short, slender, tooth-like, 

 horizontal laminee, entering but a short distance ; umbilicus nearly closed ; 

 peristome white, thickened, slightly reflected. 



Nearest allied to H. ariadne, Pf.^ {CoucMana, Lea, Proc. Acad. N. S., anno 

 1857, April, p. 102.) I have compared it to Mr. Lea's type, and find it to be 

 quite distinct. The latter is not perforated and has a very different arrange- 

 ment of teeth. That H. Loisa is not a less developed specimen of H. Couchiana 

 is shown by the fact of its being twice the size. Mr. Lea's shell has the parie- 

 tal tooth more angular, flexuose, and entering farther into the aperture ; the 

 teeth on the right lip are not horizontal, heavier and longer, and extend to the 

 edge of the peristome, where they are very solid and elevated, while in io/sa 

 they are slender laminee, removed within the aperture. 



Helix (Polygra) Mooreana. Testa orbiculato-depressa, carinata, umbili- 

 cata, albida ; spira obtusa, plus minusve elevata ; anfr. 6, vix convexiusculi, 

 striati, ultimus infra carinam non rotundatus ; sutura impressa ; subtus strias 

 minus distinctae ; anfr. 1]-, ultimus carina valde producta. anfr. alterum et 

 umbilicura profundum pene tegens ; apertura orbicularis, contracta, tridentata ; 

 perist. album, incrassatum, vix reflexiusculum, margine basali dentibus duobus 

 curvatis marginalibns sinu parvulo orbiculari separatis, armato ; plica alba 

 rectangularis, dentiformis, excavata, in medio aperturre projecta ad columellam 

 adnata, et perist. margines connectans. 



Diam. maj. 82, min. 7, alt. 3 mill. 



Hab. Washington Co., Texas. Fr. Moore I 



Shell orbicular, depressed, white, carinated, umbilicated ; spire more or less 

 depressed, obtusely rounded ; whorls 6, distinctly striated, hardly convex ; 

 suture impressed ; below the carina the body whorl is not rounded, but slants 

 down to the base which is parallel with the suture ; below, the stria; are less 

 distinct ; at the umbilical region only 1| whorl is visible, the outer one strongly 

 carinated so as to conceal a portion of the umbilicus and a great part of the 

 remaining whorl ; the umbilicus is very small, but perforates the shell to the 

 apex, showing all the volutions with the aid of a lens ; aperture rounded, con- 

 tracted by three teeth ; lip heavy, broad, white, hardly reflected, near the basal 

 extremity, quite on the edge, armed with two short, incurving teeth, separated 

 by a small rounded sinus ; on the columella there is a tooth-like fold, square, 

 projecting across the aperture, its extremities joining those of the peristome. 



It is difficult to express correctly in words the s{)ecific differences of the vari- 

 ous Polygyra;. This shell combines the characteristics of several American 

 species. It has the spire of H. monodon, Rackett, and the columellar fold of 

 Dorfeuilleana, Lea, as figured Tr. Am. Phil. Soc. vi., pi. xxiv., f. 118. The 

 teeth are placed on the inner edge of the peristome, as in Texasiana, Mor., and 

 the curious carination at the umbilical region resembles that of pustula, Fer., 



[October, 



