76 AURICULID.S:. 



§ 1. Umbilicus more or less open and pervious. 



1. Plecotrema typica. 



Shell umbilicate, ovate-conic, solid, crowdedly grooved spi- 

 rally, not shining, of a pale rusty colour, with brown bands ; 

 spire produced, with rather convex outlines, and the apex 

 pointed ; whorls nine, indistinct, the last about as long as the 

 spire, somewhat turgid above, compressed round the open and 

 deep umbilicus, with a strong, varix-shaped crest behind the 

 aperture, which is scarcely oblique, narrow ; parietal plaits two, 

 the upper nodiform, the other deeply bifid; columella! plait 

 transverse ; peristome simple, with the margins united by a 

 callus ; right margin thickened and bidentate within ; columellar 

 margin spreading. Length 8, breadth 4 mill. 



Plecotrema typica, H. and A. Adams inProc. Z. 8. 1853, p. 120; 

 Gen. rec. Moll. ii. p. 240. pi. 82. f. 4. 

 Pfr. Syn. Auric, n. 96 ; Mon. Auric, p. 100 ; Novit. Conch. 

 i. p. 16. n. 26. t. 5. f. 12-14. 

 Hah. Pido Penang {Taylor); Tachoban, Isle of Zeyte (H. 

 Cuming). 



2. Plecotrema concentna. 



Shell umbilicate, ovate-conic, solid, distinctly striated longi- 

 tudinally, and crowdedly grooved spirally, dirty fulvous ; spire 

 conic, acute ; suture indistinct ; whorls nine, flat, the last about 

 as long as the spire, slightly angled above, compressed round 

 the umbilicus, which is funnel-shaped and not pervious, with a 

 strong crest behind the peristome; aperture scarcely oblique, 

 narrow ; parietal plaits two, the upper nodiform, the other ob- 

 soletely bifid; columellar plait small, horizontal; peristome 

 nearly simple, with the margins united by a rather thick de- 

 posit; right margin bidentate within; columellar margin di- 

 lated, spreading. Length 6|, breadth 4 mill. 



Plecotrema concinna, H. and A. Adams in Proc. Z. S. 1853, p. 122 ; 

 Gen. rec. Moll. ii. p. 241. 

 Pfr. Syn. Auric, n. 97 ; Mon. Auric, p. 101. 



Hab. Moreton Bay, Australia. 



3. Plecotrema lirata. 



Shell umbilicate, ovate-conic, thick, sculptured with very 

 close-set spiral furrows, not shining, of a dirty brownish colour ; 

 spire conic, with the outlines somewhat curvilinear, and the 

 apex pointed; whorls nine, indistinct, flat, the last about as 

 long as the .spire, compressed at base, crested behind the aper- 



