306 



Cyclostrema pachyston, n. sp. PL xxix., rig. 10. 



Shell orbicular, depressed, of five whorls, spire slightly 

 elevated. First two and a half whorls convex, smooth, fol- 

 lowed by a spire-whorl, with five equidistant spiral lirse. 

 Body-whorl upper surface flatly sloping, nearly smooth, with 

 fine curved axial wrinkles antecurrent just below the suture, 

 then obliquely retrocedent. Side convex, with four well- 

 marked spiral lirae to the periphery. Base rounded with 

 about eight spiral cords, very flat and low, separated only by 

 incisions. Umbilicus minute, nearly filled up by flat callus 

 expansions of the inner lip, producing rude curved radial 

 wrinkles. Aperture round ; outer lip oblique, thin and 

 simple, somewhat crenulated outside by the lirge ; basal part 

 thicker and smooth; inner lip thin where applied to the base 

 of the body-whorl, and expanding beyond the concave colu- 

 mella as a thick shiny smooth callus to the centre of the per- 

 foration. 



Dim. — Greatest diameter, 215 mm.; smallest, 2 mm.; 

 height, 1'5 mm. 



Locality. — 62 fathoms, north-west of Cape Borda, 10 dead. 



The largest example is 3'2 mm. in diameter. In the 

 larger shells the perforation becomes more ojDen, and its sides 

 are radially wrinkled. 



Cyclostrema denselaminatum, n. sp. PI. xxix., fig. 9. 



Shell opaque-white, minute, turbinate, of four whorls, 

 nearly detached, rapidly increasing. Protoconch one and 

 three-quarter whorls, flatly convex, smooth. Spire-whorls 

 convex. Sutures deep. Aperture circular, complete, de- 

 tached from the base of the body-whorl; border simple. Um- 

 bilicus moderate, perspective. Sculpture begins abruptly 

 from the protoconch; valid axial laminae, about as high as 

 wdde, and one-half or one-third as wide as the interspaces, 

 crowded, nearly 50 in the body-whorl, completely encircling 

 the whorls and so visible in the umbilicus. Fine hair-like 

 \spiral threads, about 40 in the body-whorl, less crowded on the 

 base and near the suture than on the periphery. 



Dim. — Greatest diameter, r55 mm.; smallest, 1'4 mm.; 

 height, 1*1 mm. 



Diagnosis. — Scala nepeanensis, Gatliff, is more elate and 

 has fewer axial laminae. Cyclosirema anf/eli, Ten. Woods, is 

 more elate and has a smaller perforation. C. johnsfoni, Bed- 

 dome, is similar in shape and has crowded axials, but has no 

 spirals. 



Locality. — Type from 62 fathoms, north-west of Cape 

 Borda; Backstairs Passage, 22 fathoms, 6 dead. 



