MARINE MOLlirsCA OP MADEIEA. 263 



a smaller and more narrowed apex, and a more turned-over tip, 

 the moutli is narrower, the pillar-edge more prominent, and 

 there is an umbilical chink. 



!Fam. Pleueotomaeiid^. 



Gen. ScHiSMOPE, Jeffr. 



32. ScHiSMOPE DEPEESSA, n. sp. (Figs. 32 a, 32 l, 32 c.) 

 STiell very small, hyaline white with a tinge o£ pale brown, 

 obliquely depressed, flattened above, with a minute apex and 

 linear suture, a large sub-circular mouth, and a large half- 

 funnel shaped fissure for an umbilicus; its last whorl is cari- 

 nated on its upper surface by the raised edges of the scar 

 of the respiratory orifice. Sculpture — Longitudinals : there are 

 on the earlier whorls close-set radiating riblets which are some- 

 times obsolete, and in all cases degenerate on the base and 

 on the later whorls into mere threadlets widely parted ; the 

 whole surface is further scored by sharp radiating curved 

 scratches. Spirals : nearly half of the last whorl is keeled (but 

 not angulated) by the canal-ridge which rises well within the peri- 

 phery, and leads to the narrow oblong respiratory orifice which 

 is formed in the shell as it grows, and is plu2:ged up at its pos- 

 terior end as the shell-edge is pushed forward in growth ; along 

 the interior of the shell the edges of the disused canal project in 

 a minute sharp-edged flange ; on the outside from the front of the 

 orifice on to the mouth-edge an irregular depression (visible 

 within the mouth also) scars the shell-surface ; the shell-substance 

 shows no trace of this interruption in the earlier whorls, and tbe 

 strong oblique downward bend of the last whorl only arises with 

 the expansion of the last whorl and very shortly before the 

 respiratory orifice claims a place. Above the keel the flat surface 

 is scored by about ten fine threads and furrows which become 

 fainter and sparser near the suture ; below the carina the whole 

 surface is similarly but more strongly and irregularly scored. 

 Spire very much flattened, apex hardly raised. Whorls barely 

 three, of sudden increase. Suture scarcely impressed. Mouth 

 large, gibbous like a nearly-full moon, excessively oblique. 

 Outer lip greatly descending, flat above, well rounded but 

 scarcely patulous below, where at the pillar-point it forks and 

 the outer edge of it sweeps round a little within the edge of the 



