THE NAUTILUS. 

 POTAMOLITHUS JACUHYENSIS, N. SP. 



BY H. A. PILSBRY. 



Shell turbinate globose, the last whorl with a " shoulder," pro- 

 duced by an obtuse but distinct angulation of the whorl above its 

 middle ; solid and strong, smooth, except for light growth lines, cov- 

 ered with a strong, dark brown cuticle, becoming reddish on the spire 

 and green behind the outer lip. Spire low conic, whorls about 4 , 

 those of the spire but slightly convex, the last large, obtusely angular 

 above, rather flattened peripherally, the base somewhat concavely 

 tapering. Aperture large, rather dilated, oblique, livid within, be- 

 coming blue-white toward the lip and on the inner margin ; peristome 

 continuous, blunt, thickened within at the upper angle, the outer lip 

 a little waved or sinuous, inner margin heavily calloused, rounded, a 

 narrow columellar crescent defined by an arcuate angle. Alt. 0.5, diaui. 

 5.3, greatest length of aperture 5 mm. 



Rio Jacuhy, Rio Grande do Sul, Brazil (Dr. H. von Ihering) 



This species differs from P. lapidum in the angular last whorl, 

 more heavily calloused, parieto-columellar margin, much larger aperture, 

 and the angle defining a narrow, crescentic columellar area. P. orbig- 

 ni/i Pils. is more closely allied than any other known species, but iu 

 that the body whorl is more distinctly biangular, the outer lip is more 

 expanded and distinctly varixed, etc. 



The species of this genus already described by d'Orbigny and my- 

 self, came from La Plata, Parana and Uruguay rivers. The present 

 form is interesting as being from the Jacuhy. a stream flowing into 

 the Atlantic instead of into La Plata. 



For previous references to this genus, under the names .Paludes- 

 trina, Lifhoglyphusand Potamolithus, see d'Orbigny, Amer. merid., 

 p. 382; E von Martens, Malak. Blatter, 1868, p. 192 ; H. von 

 Ihering, Malak. Blatter (n. F.) VII, p. 9o, and Pilsbry, Nautilus X, 

 pp. 86, 119. 



^ 

 KEMARKS ON THE AMERICAN SPECIES OF CONULUS. 



BY HENRY A. PILSBRY. 



In most parts of the world there occur small land snails with thin, 

 yellow or brown glossy shells, conical, pyramidal or teocalli shaped, 

 with the axis imperforate or barely perforated. The foot has pedal 

 grooves and the side-teeth are thorn- shaped, with two or more points. 



