142 PHASIS-TRACHYCYSTIS. 



but narrow; mouth lunar-ovate, lip a little reflexed at the col- 

 umellar margin. (M. & P.) 



Group of H. planti. 



P. PLANTI Pfr. (Vol. Ill, p. 105). PL 43, figs. 57, 58, 59. 



Dohrn, in refiguring this species (Contin. Conchyl. Cab., p. 622, 

 t. 178, f. 29, 30, 31) remarks that although Pfeiffer calls the species 

 " longe pilosa," he cannot substantiate the statement, for it has no 

 hairs or bristles, but only strips of the membranous cuticle which 

 have become detached from the riblets, and look like hairs. 



This peculiarity, with the lower situation of the peripheral angle, 

 will separate Planti from Africa. 



P. AFRICA A. D. Brown. PL 43, figs. 55, 56. 



Shell very narrowly umbilicated (the umbilicus about one-eigh- 

 teenth the diameter of the shell), depressed above, convex below, 

 obtusely angular at the circumference ; thin and rather fragile, light 

 horn-color, nearly lusterless. 



Spire slightly raised, the apex small, raised ; the first whorl 

 smooth, following whorls sculptured with delicate, spaced cuticular 

 laminae, hardly seen except under a lens, and becoming more widely 

 spaced and more inconspicuous on the last whorl ; under a strong 

 lens the surface is seen to be very closely and extremely finely 

 spirally striated both above and below. Whorls 5, slightly convex, 

 the last subangular, convex below, not descending. 



Aperture but little oblique, lunate-oval ; outer lip thin, a little 

 expanded ; columellar lip arcuate, broadly reflexed, partly conceal- 

 ing the umbilicus. 



Alt. 6, diam. 9'6 mill. Adult specimen. 



Alt. 5*5, diam. 8*5 mill. Adult specimen. 



Great Brakke, South Africa. 



H. africce A. D. BROWN, Amer. Journ. Conch, i, 1865, p. 136. 

 PFR., Monogr. vii, p. 459 ; Conchyl. Cab., p. 527, t. 162, f. 8, 9. 



This species differs from H. planti as described by Pfr. in lacking 

 hairs, and from the same species as figured by Dohrn, in having the 

 peripheral angulation situated higher on the whorl. The membra- 

 nous riblets are a trifle ragged on the edges, but in none of the eight 

 specimens before me are there any hairs. The above description is 

 from Brown's types, now in the collection of the Academy. 



