658 PROCEEDINGS OF THE ACADEMY OF [DeC, 



the type by being more slender, more irregularly flammulate, less 

 distinctly shouldered below the sutures, and by having the spiral 

 sulci more persistent and deeper and the aperture broader and 

 shorter. 



Alt. 21, diam. 9, length of aperture 9, width 4.25 mm.; whorls 3|. 



AMNICOLID^. 



• Genus LITTORIDINA Souleyet. 



Littoridina manni n. sp. PI. XXVI, fig. 15. 



Shell distinctly rimate, but not perforate, rather thin, ovate conic, 

 of a dark olivaceous-yellow color, lightly marked by growth lines, 

 crossed by more distinct, irregularly sized and spaced spiral costulse, 

 showing under a glass on the last two whorls; spire straightly conic, 

 apex minute, slightly obtuse and dimpled. Whorls 4|, all moderately 

 convex and regularly increasing; sutures well defined, but not im- 

 pressed. Aperture veiy slightly oblique, ovate, white; peristome 

 simple, continuous, very evenly curved, and showing a very delicate, 

 whitish thickening within; outer lip joining the parietal wall at an 

 angle of about ninety degrees; inner margin continuous, in contact 

 with the preceding whorl; a delicate, deeply sinused callus joining 

 the extremities and extending well within the aperture. Alt. 3.17, 

 diam. 2, alt. of mouth 1.15 mm. 



Two specimens differing slightly in size were taken on the north 

 bank of the chief affluent of Papary Lake near its mouth. 



The species resembles L. charruana Orb., but differs by the presence 

 of spiral striations and by the distribution of callus within the mouth. 

 I have named the species for Mr. W. M. Mann, the entomologist 

 of the Expedition, who alone, of the members of the Expedition, 

 accompanied me on that portion of the trip extending up the Amazon 

 and to the ^Madeira and Mamore Rivers, and who aided me greatly 

 in the collection of mollusks. 



Genus IDIOPYRGUS Pilsbry. 

 Idiopyrgus pilsbryi n. sp. PI. XXVI, figs. 13, 14. 



Shell perforate, turreted, solid, opaque, olive-green, becoming 

 lighter on the last whorl; spire tapering regularly to the apex, which 

 is eroded in both specimens; surface smooth except for faint growth 

 lines, rather dull. Whorls 4|, all strongly convex, separated by deep 

 sutures. Aperture oval, oblique, the basal margin only slightly 

 advanced, the outer lip retracting upward; peristome continuous, 

 outer lip slightly expanded, somewhat thickened within, with a 

 rounded sinus jiist below the upper insertion and a small sinus at 



