20 



3- Nnculana {Nuculand) robsoni nom. nov. (Plate I, figs. 19, 20). 



1871. Laeda acuminata Sowerby (nec Buch) in Reeve Conch. Icon. XVIII, Laeda^ pi. VIII, 

 fig. 50. 



Leda acuminata is preoccupied by Buch ^) in 1833, and I, therefore, propose to associate 

 Sowerby's species with the name of my friend Mr. G. C. Robson of the British Muséum (Nat. 

 Hist.), London, as a small return for the many favours extended to me during the time I was 

 workino; in the British Muséum. 



The very pecuHar shape, the very regular sculpture of the shells and the strongly developed 

 hinge consisting of about 20 closely placed teeth on each side are characteristi,c of the species. 



Distribution : — The types of the species in Muséum Taylor were without any habitat, 



The "Siboga" Expédition collected a good séries of shells from a depth of 9 mètres at 

 the Anchorage off Djangkar, Java (St. 4). 



4. NîLciilana [JVtictilana) proatmbens sp. nov. (Plate I, figs. 21, 22). 



The following is a description of this new species: — Shell small, ovately trigonal, with 

 numerous thick concentric ribs narrower than interstices; with a sinuous elevated ridge running 

 from umbo to pointed rostrum behind; somewhat acuminate anteriorly, with a shallow groove 

 running alongside lunule to ventral margin near anterior angle ; umbones elevated, rounded, not 

 approximating in middle, lunule shallow, escutcheon almost rhomboidal, narrow, concave; ventral 

 margin greatly arched ; hinge-plate well developed, anterior séries with 12, posterior with 10 

 teeth. Shell of a pale straw colour, nacre shining white. 



Measurements of Holotype : — Length 5.8 mm., height 3.9 mm., diameter 6 mm. 



Habitat: — A single shell of this interesting species was brought up in a deep sea trawl 

 at St. 2 1 1 (5°4o'.7S., i20°45'.5E., 1158 mètres). 



Remarks : Nticidana {Nnculana) procnmôens resembles N. {N.) reticnlata (Hinds) ") from 

 the Philippines, but the sculpture of the two species is quite différent. 



5. Nttcîdana [Nnculana) bathybia sp. nov. (Plate I, figs. 23, 24). 



The following is a description of this new species : — Shell small, subovate with numerous, 

 fine, subconcentric striae covering the surface; ridge from umbo to rostrum only slightly marked; 

 umbones elevated, angulated; anteriorly acuminately rounded, without definite groove from lunule 

 to ventral margin, posteriorly narrowly angulate; lunule shallow, escutcheon narrow, deeply 

 concave; ventral margin slightly arched; hinge-plate well developed, with subequal teeth in both 

 anterior and posterior séries. Shell of a dirty straw colour, nacre shining greenish white. 



Measurements of Holotype: — Length 6.4 mm., height 4 mm.; diameter 2.8 mm. 



Habitat: — A single shell of N. (A^.) bathybia was dredgedat St. i 78 (2°4o' S., i 28° 37^.5 E.; 

 835 mètres). 



Remarks: — This species is easily distinguished by its form, very regular sculpture and 

 hinge teeth. 



1) Buch, C. L. von — In Zieten Petref. Wurtemberg, X, p. 77, (1833). 



2) See Sowerby, G. J. — in Reeve Conch. Icon. XVIII, Laeda. pi. VIII, fig. 48 (1871). 



