paululum intrante, aiigulato conjunctia, dextro larainis diiobus horizontalibus, 

 Curtis, intus positis munito ; basali dentibus duobus perpendicularibus in 

 margine positis, uno parvulo, altero majore, munito. 



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



In Provincia Mexicana Cinaloa ad flumen Mazatlan coUegit Gambel. Collect. 

 Phillips. 



Var. minor diam. maj. 10, min 1, alt. 3. In Texas habitare dicitur. Collec. 

 Mea. 



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

 slight]}' 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 

 white, 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 laminae, entering but a short distance ; umbilicus nearly closed ; 

 peristome white, thickened, slightly reflected. 



Nearest allied to H. ariadne, Pf., {Covchiaim, 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 ver^^ diflferent 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 2/Owa 

 ^ey are slender laminae, removed within the aperture. 



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

 cata, albida ; spira obtu?a, plus minusve elevata ; anfr. 6, vix couvexiusculi, 

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

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

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

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

 curvatis marginalibus sinu parvulo orbiculari separatis, armato ; plica alba 

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

 adnata, et perist. margines connectans. 



Diam. maj. 8J, min. 7, alt. 3 mill. 



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



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 striae are less 

 distinct ; at the umbilical region only 1 i 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 diSicult to express correctly in words the specific difi'erences of the vari- 

 ous P<'lygyrce. This shell combines the characteristics of several American 

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

 Dorfewlleana, Lea, as figured Tr. Am. Phil. Soc. vi., pi. xxiv., f. 118. Tb€ 

 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, 



