MACRODONTES. 29 



Apex spirally lirate ; aperture oblong, toothed, the 

 peristome free throughout, parietal tooth marginal, 

 tuberculiform, not entering ; whorls few, 5-6^. 



, p. 29. 



Genus MACRODONTES, Swainson, 1840. 



Mncrodontes SWAINS., Malacology, p. 334, type and sole species 

 J/. xowerbeyi Sw., = 0. odontostomus Sowb. 



Shell umbilicate, oblong, striate and decussate, composed of 5-6^ 

 convex whorls, the first 1^ spirally lirulate, the last becoming free in 

 front, keeled at the base. Aperture channeled below, obstructed by 

 a marginal and tubercular parietal tooth, a columellar fold bearing 

 n transverse lamella below, a subcolumellar lamella, basal, upper and 

 lower palatal folds, and a suprapalatal fold ; part or all of the teeth 

 sometimes degenerate or subobsolete ; peristome continuous, free and 

 reflexed throughout. 



The jaw (pi. 5, fig. 37, M. odontostomus) is stout, arcuate and 

 smooth, showing faint vertical striae and under very high magnifica- 

 tion. The teeth (pi. 5, fig. 38) have simple mesocones in the median 

 part of the radula, the inner marginals adding an ectocone. The 

 outer marginal teeth were lost from my preparation. 



The reproductive system (pi. 15, fig. 28, M. odontostomus} is sim- 

 ple, the organs shorter than in Odontostomus punctatissirnus. The 

 long penis has a terminal retractor muscle and vas deferens. The 

 vagina is long, spermatheca oval on a rather long duct. The lower 

 portion of the hermaphrodite duct is pressed into and imbedded in 

 the albumen gland for the whole length of the latter, being visible on 

 its concave face. Length of penis 17^, of vagina 6, of spermatheca 

 with duct 11 mill. 



Free retractor muscles : Right and left ocular and anterior foot 

 retractor bands, and the columellar muscle, separate except immedi- 

 ately at their proximal insertions; retractor of the buccal mass united 

 with the left ocular band for a very short distance proximally. The 

 right eye retractor passes between branches of the genitalia. 



The lung (pi. 15, fig. 29) is rather short, closely veined throughout, 

 the venation strongest on the cardiac side, the secondary pulmonary 

 vein well developed. Kidney triangular, short, hardly extending 

 forward beyond the pericardium. Secondary ureter wholly open. 



Distribution, southern Brazil. 



