Shell ovate, moderately inflate, white, pellucid, right margin thickened, extremities slightly 

 produced, especially the anterior one, with rather numerous ribs, of which the majority runs 

 from one side to the other and a few intermediate ones, no dorsal sulcus. Aperture rather wide, 

 especially towards the front, slightly arcuate, its right margin but little inflected, thickened 

 exteriorly, strongly crenulated by the ribs, which form from i8 to 21 teeth; anterior sinus wide, 

 posterior one narrower by a crenulated callus, columellar margin not thickened, with about 20 

 teeth, the interstices of the ribs of both the right and columellar margin granulous, the inter- 

 stices on the back smooth. 



Long. 7, lat. 5, alt. 4 Mill. 



The species resembles amongst the white ones without dorsal impression, in some respects 

 T. pelhicidula Gaskoin, which has however much more and finer ribs. One of the specimens 

 from Stat. 105 contains the soft parts and may serve as a proof that the species lives at the 

 recorded great depth. 



6. Trivia paucicostata n. sp. PI. XI. fig. 2. 



Stat. 95. 5°43'.5 N., ii9°4o'E. Sulu Sea. 522 M. Stony bottom. 3 Spec. 



Shell shortly ovate, swollen, greyish-white ,(perhaps flesh-coloured in life), with few strong 

 ribs and rather wide, smooth interstices, considerably broader than the ribs; no dorsal impression, 

 the majority of the ribs runs from one side to the other, with a few intermediate ones which 

 don't reach the centre. Aperture rather wide, running on the right side of the ventral face, 

 slightly wider at the anterior end. Right margin relatively thin, with a thickened rib exteriorly 

 and only 13 teeth, columellar margin with about 14 teeth, slightly excavated interiorly, front 

 sinus large, posterior one narrower, with a small callosity on the left side, anterior end slighty 

 rostrate or produced; interstices of the ribs on the apertural margins granose. 



Long. 8Y„ lat. 67,, alt. 5V, Mill. 



This and the next species resemble some of the South-African species by their aperture, 

 which lies on the right side of the base, and is larger than usually in Trivia. In sculpture, 

 but not in shape, it resembles T. Buttoni Melv. (Ann. Mag. Nat. Hist. Ser. 7, Vol. VI, 1900, 

 p. 209) this species is however more regularly ovate in outline, the dorsal view of the new 

 species being subtrigonal, in consequence of the blunt posterior part, in BiMoni the aperture 

 is much narrower and is situated more centrally. 



7. Trivia sibogae n. sp. PL XI, fig. 3. 



Stat. 105. 6°8'N., 121° 19' E. Sulu Sea. 275 M. Coralbottom. 3 Spec. 



Shell shortly-ovate, globose, thin, light flesh-coloured, with numerous rather strong ribs 

 and smooth interstices, which are but a little broader than the ribs, no dorsal impression; several 

 of the ribs don't reach the centre, while others run from one side to the other. Aperture rather 

 wide, slightly enlarged towards the front part, placed at the right side of the ventral face. Right 

 margin slightly involved, strongly thickened exteriorly, its inner margin with 19 or 20 teeth; 



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