1898.] NATURAL SCIENCES OF PHILADELPHIA. 471 



NEW SPECIES OF ODONTOSTOMUS FROM BRAZIL AND ARGENTINA. 



BY HENRY A. PILSBRY. 



The forms noticed below are mainly recent accessions to the col- 

 lection under my charge, received from Dr. H. von Ihering, the 

 Director of the young but progressive Brazilian institution, the 

 Museu Paulista. Three of the species belong to the subgenus of 

 Odontostom us called Macrodontes, a group characterized by the con- 

 tinuous peristome, spirally lirulate earlier whorls, and regular, fine 

 striation of the later ones, with minute and shallow but close spiral 

 incised decussating lines. This very distinct subgenus contained 

 four species: odontostomus Sowerby, jasciatus Dohrn, Grayanus 

 Pfr. and cordovanus Pfr. Dr. von Ihering's zoological explorations 

 have already nearly doubled this number. 



All of the species of Macrodontes hitherto known have the aper- 

 ture obstructed by large teeth ; but in two of the new forms, degen- 

 eratus and Dautzenberg ianus, the teeth have degenerated to such a 

 degree that they are probably no longer functional as barriers 

 against predacious arthropods. In another, paulista, the teeth are 

 more strongly developed than in any other Macrodontes. 



Odontostomus (Macrodontes) paulista Pilsbry <fc v. Ihering, n. sp. 



Shell lengthened fusiform ; rather solid; reddish-chestnut, with 

 irregular, lacerated and somewhat zigzag, obliquely longitudinal, 

 hydrophanous, cream-tinted streaks. Surface dull, very minutely 

 but sharply striated in the direction of growth lines, a strong lens 

 showing much more minute and superficial, dense, spiral striation, 

 the apical whorls spirally lirate. Whorls 6, the first turned in, the 

 rest rather rapidly and regularly increasing, moderately convex, the 

 last becoming free at the aperture, compressed behind the outer lip, 

 the trench there impressed by five pits ; base pinched into an acute, 

 produced keel ; and behind the columellar lip there are two pits and 

 a deep axial pit, with another shallow pit behind the elevated 

 parietal wall. Aperture slightly oblique, narrow, irregularly 

 oblong, obstructed by eight pliciform teeth and a strong, deep-seated 

 columellar lamina ; peristome continuous, white, reflexed through- 

 out, the outer lip with two large teeth situated like those in 0. 



