Pseudoliotia.] GASTROPODA. 157 



close to the suture, followed by 4 equally strong equidistant spiral 

 ribs, the interspaces much broader than the ribs ; the whole crossed 

 by fine, close, oblique incremental striae ; a sixth broad rib, more 

 nodulous than the others, forms a half-circle around the strongly 

 impressed umbilical area, which is ornamented with distant axial folds. 

 Colour yellowish-white, the spiral ribs maculated with brown. Spire 

 depressed, lower than the aperture. Protoconch white, of 2 spirally 

 costate flat whorls. Whorls 4, the last large, flattened below the 

 suture, then convex ; base rounded. Suture not impressed. Aperture 

 oblique, nearly circular, white and porcellanous inside. Peristome 

 thick, very little contracted, crenulated on the outside by the spiral 

 ribs, regularly convex. Columella arcuate, shining white, thick. 

 Inner lip spreading over the umbilicus, completely sealing it up, or 

 sometimes leaving a minute chink ; a white callus unites the con- 

 verging margins of the peristome. In young specimens the umbilicus 

 is open, but very narrow. Operculum not seen. 



Diameter, 3-5 mm. ; height, 3-5 mm. 



Animal unknown. 



Type in my collection. 



Hob. Stewart Island. 



Remark. The species is distinguished from the type, P. micans, by 

 the absence of radiate riblets, the discontinuous peristome, and the 

 closed umbilicus. 



Fam. VITRINELLID^, K. J. Bush. 

 Cyclostrematidce, auth., in part. Adeorbidce, Dall., in part. 



Shell small, more or less hyaline, spire varying from concave to 

 moderately elevated ; umbilicus deep, narrow to wide ; aperture 

 nearly circular ; peristome simple, more or less continuous ; colu- 

 rnellar lip often flattened and angular below ; operculum horny, multi- 

 spiral. 



KEY TO GENERA. 



A. Shell thin and delicate ; spire elevated ; umbilicus small, 



deep . . . . . . . . . . . . LISSOSPIRA. 



B. Shell nearly flat-spired, with wide, open umbilicus ; with 



spiral sculpture . . . . . . . . CIRCULTJS. 



C. Shell planorbiforrn, spire concavely depressed, umbilicus 



wide, nucleus turned downward . . . . . . CYCLOSTREMELLA. 



Genus 1. LISSOSPIRA, K. J. Bush, 1897. 



Lissospira, Bush. Trans. Connecticut Acad., x, 1897, 129. Type : Cyclo- 

 strema proximo, Tryon. 



The radula consists of numerous rows of delicate teeth ; each row 

 having 1 broad central or median tooth, with a broad, blunt, delicately 

 serrate, curved tip, and on either side 4 more slender lateral teeth, 



