25 



2. Yoldia sp. 



A single left valve of a species of Yoldia brought up in a deep sea trawl at St. \ 8 

 (7°28'.2S., ii5°24'.6E.; ioi8 mètres) is quite unlike any of the already known species. With 

 a single, badly worn valve, however, I do not feel justified in describing it as a new species. 



Subfamily Malletiinae. 

 Genus Malletia Desmoulins. 



1832. Malletia Desmoulins, Act. Soc. Linn. Bordeaux, V, p. 85. ' , 



1833. Solenella Sowerby, Proc. Zool. Soc. London, p. 197. 

 1840. Ctenoconcha Gray, Synop. Conch. Brit. Mus., p. 135. 

 1858. Malletia Adams, H. & A., Gen. Rec. MolL, II, p. 549. 

 1860. Solenella Hanley in Sowerby, Thés. Conch., III, p. 164. 

 1886. Malletia Fischer, P., Man. Conchyliol., p. 986. 



1897. Malletia Verrill & Bush, Amer. Journ. Soi., (4) III, p. 56. 



For a good description of this genus référence may be made to Verrill & Bush's paper 

 cited above. The génotype is Malletia chilensis Desmoulins. 



1. Malletia conspicua Smith. 



1895. Malletia conspicua Smith, Ann. Mag. Nat. Hist., (6) XVI, p. 17, pi. II, fig. 12. 

 1897. Malletia conspicua Smith, lUustr. Zool. 'Tnvestigator", MolL, pi. II, figs. "ja, b. 



As Smith noted in his description M. conspiczta is closely allied to M. arrottana Smith 

 from the Arrou Islands, but the form of the shell and the sculpture are différent in the two species. 



Distribution : — The types of M. conspicita were dredged in the Arabian Sea at a depth 

 of 636 fathoms. 



In the "Siboga" collection there are shells brought up in deep sea trawls at St. 18 

 (7°28'.2S., ii5°24'.6E., 1 01 8 mètres), St. 48 (8°4^7S., 1 18°44'.3 E.,. 2060 mètres), St. 52 

 (9° 3^4 S, 1 19° 56^.7 E., 959 mètres). St. 300 (10° 48'. 6 S., i23°23'.iE., 918 mètres) and St. 314 

 7° 36' S., II 7° 30'. 8, 694 mètres). Thèse finds greatly extend the range of the species. 



2. Malletia erronea sp. nov. (Plate I, figs. 40 — 43). 



The following is a description of this new species: — Shell of large size, moderately 

 thick, transversely oblong, elongate, compressed; anteriorly truncate; posteriorly arcuate above, 

 obliquely truncated below, very inequilateral ; anterior dorsal slope somewhat convex, posterior 

 almost straight; ventral margin almost straight; umbones rather prominent, acuminately rounded; 

 sculpture consisting of close-set, concentric striae, rather irregular on posterior third of shell ; 

 two feebly developed radiating ridges from behind the umbones to posterior ventral margin of 

 shell; hinge-plate well developed, with about 20 teeth anterior to and about 30 posterior to 

 umbo. Shell of shining pale straw to brownish colour; nacre shining white. 



Measurements of Holotype : — Length 18.6 mm., height 8.7 mm., diameter 5 mm. 



Habitat: — A single shell of M. erronea was brought up in a deep-sea trawl at St. 300 

 (io°48'.6S., i23°23'.iE., 918 mètres). 



SIBOGA-EXPEDITIE LlIIf. 4 



