34 MACRODONTES. 



slender contour, basal instead of baso-peripheral position of the keel, 

 which is nearly straight instead of being spirally curved, and in the 

 longer and narrower aperture, which is consequently more filled by 

 the large teetb. Tbere is also one more tooth than in M. odontostomus 

 or M. grayanus fascialus, and the striation is much finer. M. gray- 

 anus differs strongly in the less tapering and quite differently-shaped 

 base, as well as in lacking the median tooth of the outer lip, and in 

 coloration ; but the angular outline and narrow form of the aperture 

 are similar. 



M. DAUTZENBERGIANUS Pilsbry. PI. 13, figs. 95, 96, 97. 



Shell oblong-ovate, thin, light chestnut with a golden sheen, and 

 sparse, narrow, oblique or zigzag creamy hydrophanous markings 

 (absent on some specimens) ; surface dull, with very minute but 

 regular and sharp striation along the lines of growth, and much finer, 

 shallower, close spiral lines ; tlie apical 1 J whorls delicately spirally 

 lirulate. Whorls 5, the first with in-turned tip, the rest rapidly in- 

 creasing, convex, the last becoming very shortly free at the aperture, 

 somewhat compressed behind the outer lip, and with three small pits 

 there ; the base pinched into a short, strong keel ; behind the colu- 

 mellar lip two-pitted, with a deep umbilical fissure. Aperture irreg- 

 ularly oblong ; peristome continuous, flesh-colored, narrowly reflexed, 

 orange-brown within, the upper margin with a small blunt tooth, outer 

 lip with four small or minute tubercular teeth within, the lowest low 

 and wide, the upper two (upper palatal and suprapalatal) minute and 

 acute, whitish ; basal lip with one low, wide tooth, the columella 

 with a strong oblique fold upon which a minute whitish denticle is 

 placed, another one being situated below the columellar fold. 



Alt. 26, diam. 11^ mill.; length of aperture 12, width 7 mill, (in- 

 cluding peristome). 



Brazil : Raiz de Serra, Prov. Sao Paulo (Dr. H. von Ihering). 



0. (Macrodontes] dautzenberyianus PILSBRY, Proc. Acad. Nat. 

 Sci. Phila., 1898, p. 472 (Dec. 12, 1898). 



This species, to which we have attached the name of a distin- 

 guished French conchologist, is obviously a Macrodontes, agreeing 

 with the species of that genus in the positions of the denticles ; 

 but in our species the armature of the aperture has degenerated to a 

 series of very small denticles. For the rest, the form is more obese 

 than any other known Macrodontes. 



