740 ON SHELLS FROM PERAK AND NICOBAR ISLANDS. [Dec. 2, 



ultimo maxima, rotundato, basi vix convexo ; apertura superne 

 contractu, in/erne late dilatata, margine columellari callose in- 

 crassato, retrorsum paululum deflexo, margine externa convexe 

 rotundato. 

 Long. 2\ (vix), diam. 1^- mill. 



Another shell found in the same locality by Dr. Townsend. The 

 sculpture and characters of the aperture are admirably represented 

 by the figure ; the last whorl but one, however, should be consider- 

 ably more convex and consequently less turreted and less conspicuous ; 

 the base of the last whorl is a shade too convex, giving the shell an 

 umbilicate appearance, which it does not possess (G. N.). 



Georissa semisculpta, n. sp. (Plate LIX. figs. 3, 3 a.) 



Testa parva, solida, viridescens, imperforata ; anfractu ante- 

 penult imo valide sulcato, sulcis concentricis atque approximatis, 

 ultimo subcompresso ,basi planiusculo, superne concentrice valideque 

 sulcato, inferne Icevi ; apertura superne perangusta, inferne late 

 dilatata, margine columellari incrassato, abrupte retrorsum deflexo 

 ac callositate validissima regionem umbilicalem tegente instructo, 

 margine externa inferne subangulato. 

 Diam. (ult. anfract.) 2 mill. ; alt. apert. 0'05 inch. 

 A single mature specimen, with the spire unfortunately broken, 

 was found by Dr. Townsend in the Buket Pondong cave in Perak. 

 It differs so conspicuously from every other known species, and would 

 be so easily recognized again, that I have not hesitated to describe 

 it, though I do not usually do so when I possess only a unique 

 specimen. The figure is perfect (G. N.). 



EXPLANATION OF THE PLATES. 

 Plate LIX. 



Fig. 1. la, lb. Mkrocystina townsendiana, n. sp., x20, p. 736. 



2. Ennea perakensis, n. sp., x8, p. 735. 



3. 3a Georissa semisculpta, n. sp., X 12, p. 740. 



4. Acmclla moreletiana, n. sp., x24, p. 737. 



5. roepstorffiana, n. sp., x24, p. 737. 



6. Georissa monterosatiana, n. sp., x!2, p. 739. 



7. Papisoma ?, young, X 24, p. 736. 



8. Ckmsilia?, young, X 24, p. 736. 



Plate LX. 



Fig. 1, la, lb. Opistliostoma perakensis, n. sp., x24, p. 738. 



2, 2 a, 2 b. - pauluccice, X 24, p, 738. 



3, 3 a. Diplommatina crosscana, n. sp., x24, p. 738. 



4, 4 a, 4 6. mirabilis, n. sp., x24, p. 739. 



5, 5 a. Palaina superba, n. sp x8, p. 739. 



