96 ODONTOSTOMt S. 



lamella well within on the parietal wall, bifid at its outer end; one 

 very obliquely entering lamella on the columella ; and a compressed 

 upper palatal fold within the outer lip near its middle. Besides 

 these there are in some specimens a small basal fold within the basal 

 lip near the foot of the columella, and a suprapalatal fold within the 

 outer lip above the upper palatal fold ; one or two other folds being 

 developed in some individuals. Peristome expanded. 



Alt. 19-20, diam. 9, length of aperture 8^-8-^ mill. 



Argentina: Bahia Blanca, in intervals of the dunes bordering the 

 bay (Parchappe). Sierra Ventana mountain system and along the rivers 

 arising therein, Rio Naposta, Rio Sauce-Chico, etc., and draining 

 into the northern shore of Bahia Blanca. Not extending southwest 

 to the drainage of the Colorado river, nor into the Sierra del Azul, 

 etc. (Doering). 



Helix patagonica ORB., Mag. de Zool., 1835, p. 22. Pupa sower- 

 biana \ SLY. patagonica ORB., Voyage, p. 321, pi. 41 bis, f. 17, 18 

 Cyclodontina patagonica, BECK, Index, p. 88. Bidimus dentatas 

 var. 6, PFR., Monogr. ii, p. 87. Bulimus patagonicus Orb., PFR., 

 Monogr. iv, p. 438. Plagiodontes patagonicus d'Orb., DOERING 

 Informe Oficial de la Comision Cientifica agregada al estado mayor 

 general de la Expedicion al Rio Negro (Patagonia), Entr. i, 

 Zoologia, p. 68, pi 1, f. 7, 8 (1881). Odontostomus (Plagioduntes) 

 iheringi PILS. & VAN., Proc. Acad. Nat. Sci. Phila., 1898, p. 473. 



The specimens described above are what I formerly described as 

 0. iheringi (figs. 23, 24); but the full information on 0. patagonicus 

 given by Doering shows that they are referable to that species. 

 D'Orbigny described patagonicus from bleached shells from the 

 shores of the Bay, larger than those before me from the Sierra, and 

 having the peristome strongly thickened. The original figures are 

 copied on my plate 14, f. 20, 21, and the original description here 

 follows : 



Shell short, ventricose, subperforate, thick, smooth ; spire conic, 

 whitish, the apex obtuse, striated. Whorls 7; suture fiat. Aperture 

 mask-like, rounded, with three large teeth, two on the columellar 

 side. Columella fiat, thick; lip very thick, reflexed. Length 22^, 

 diam. 11 mill. (Orb.) 



Usually patagonica has but three teeth, but some individuals have 

 besides these, some other small ones, frequently but slightly indi- 

 cated, but located as in dentatus. The form of the shell is always 

 more swollen and shorter than in that species. (From Orb., Voy.) 



