THE NAUTILUS. 87 



. Depressed ; periphery with a strong, cord-like keel ; back 

 of body whorl gibbous below suture; umbilical area mod- 

 erate or large, bounded by a keel. Alt. 5'2, diaru. 6 mm. 



P. RUSHII n. sp. 



. Globose, without keels ; periphery rounded ; no ridge or 

 hump on the back ; umbilical area small, with angular 

 edge ; yellowish or olivaceous-brown, unicolored or with 

 subsutural and superperipheral green bands. Alt. 5, diam. 

 5'4 mm. P. IHERINGI n. sp. 



II. No groove on face of the columella. 



a. With 5 or 6 spiral keels, all, or the upper two with acute 

 tubercles : operculum with several whorls. Alt. 8-9, diam. 



10 mm. P. MULTICARINATUS Mill. 



an. Shell carinated or angulate, without tubercles. 



b. Peripheral keel visible on the penultimate as well as 

 the last whorl ; lip expanded or varixed. 

 e. Trochoidal, with acutely, straightly conic spire, 

 compressed median peripheral keel, a small sub- 

 sutural cariiia. and a basal keel defining a very 

 large umbilical tract. Aperture much contracted, 

 the lip varix very high, recurved above periphery, 

 the highest point of recurved lobe connected with 

 lip-edge by a short oblique rib. Alt. 5'2, diam. 



(J mm. P. Mlf'ROTHAUMA n. sp. 



cc. Trochoidal, with high conic spire and flattened 

 base and acute peripheral keel ; surface smooth 

 above and below the keel, whorls flat above, the base 

 slightly convex ; umbilical area very narrow, in- 

 conspicuous ; lip varix narrow, near the lip edge. 

 Alt. 5, diam. 5 mm. P. HIDALGOI n. sp. 



ccc. Elevated turbinate, with an acute peripheral 



keel, convex above and below it ; lip expanded. 



Alt. 5, diam. 5 mm. P. PERISTOMATUS Orb. 



bb. Peripheral keel or angle concealed on the penultimate 



whorl. 



c. Lip varix very strong, recurved above ; periphery 

 hardly angular, base convex, back of body whorl 

 with a spiral rib below the suture ; aperture much 

 contracted ; no columellar area defined. Alt. 5, 

 diam. 5* mm. P. DINOCHILUS n. sp. 



