73 



Anchorage (St. 240), Buka or Cyrus Bay (St. 299), Anchorage east of Dangar Besar, Saleh Bay 

 (St. 313) and Anchorage east of Sailus Besar, Paternoster Islands (St. 315). 



3. Modiohis {Modiohts) flavidtts (Dunker). (Plate II, figs. 27, 28). 



1856. Volsella flavida Dunker, Proc. Zool. Soc. London, p. 364. 



1857. Perna fiavida Adams, H. & A., Gen. Rec. MolL, II, p. 517. 



1860. Modiola flavida Reeve, Coiich. Icon., X, Modiola, pi. X, fig. jj (sp. 64). 



1882. Modiola flavida Dunker, Ind. MolL Mar. Japon., p. 223. 



1887. Modiola flavida Clessin in Martini Chemn. Conch.-Cab. (N. F.), VIII (3), Myttlidae,^. 112, 



pi. XXVIII, fig. 5. 

 1890. Modiola flavida Paetel, Cat. Conch. Samm., III, p. 196. 

 1896. Modiola flavida Casto de Elera, Cat. Sist. Filip., p. 793. 



1903. Modiola flavida Smith, Faun. Geogr. Maldive, Laccadive Archipel., II, p. 623. 

 1905. Modiola flavida Hidalgo, Cat. Filip., p.* 363. 

 191 1. Modiola arata Pelseneer (nec Reeve), "Siboga" Lamellibranches (Anat.), p. 16, pi. IV, fig. 4. 



The soft parts of this species were described by Pelseneer as those of M. arata Reeve. 

 It is a much less elongate, proportionately much deeper and more swollen species, with a much 

 narrower post-dorsal wing and without any definite keel at the anterior side ; such as is found 

 in M. arata. 



Distribution : — M. {M.) flavidus was described from the Bay of Manilla in the 

 Philippines, and has also been recorded from Japan. 



The "Siboga" Expédition collected mostly half grown shells from Macassar (St. 71), Banda 

 Anchorage (St. 240), Tuai Anchorage, Kei Islands (St. 258), Rumah Kuda Bay, Roma Island 

 (St. 279) and Anchorage east of Dangar Besar, Saleh Bay (Stat. 313). 



4. Modiohts {Modiohis) dîibitis sp. nov. (Plate II, figs. 29 — 31). 



The following is a description of this new species : — Species of small size ; cylindrically- 

 oblong, narrow, widest behind middle of shell ; valves moderately convex in front of centre of 

 shell; umbones situated some distance from anterior margin, moderately inflated, umbonal ridge 

 strong, rounded, becoming compressed and broader towards posterior end; dorsal margin 

 somewhat raised from centre to posterior margin, with which it forms an angulate somewhat 

 curved margin; ventral margin slightly concave; posterior margin narrowly rounded, lower half 

 almost straight; anterior margin separated from umbonal région by a deep notch, narrowly 

 rounded; sculpture consisting of low, somewhat irregular concentric threads, most of which 

 appear to correspond with régions of growth. Periostracum of a pale greenish yellow colour; 

 interior white, not glossy. Length 7.5 mm.; height 2.6 mm.; diameter 2.2 mm. 



Habitat: — The Holotype, on which the above description is based, and a young left 

 valve were brought up in a trawl at St. 297 (io°39''S., i23°40^E.; depth 520 meter) to the 

 east of Rôti Island. 



Remarks: — The new species for which I hâve proposed the name Modiohis [Modiohis) 

 dtidius does not correspond to any previously known species of the genus. Its subgeneric position 

 is rather doubtful, but it appears to come nearer most species of the subgenus Modiohis^ s. s. 



SIBOGA-EXPEDITIE lAUC. 



