51 



alike and fragments of both species, showing only the anterior parts, could easily be mistaken 

 for each ether. Posteriorly however the difference is marked. In stapes the longitudinal angles 

 are much sharper, the arch on the convex side is narrower, and higher in proportion to the 

 Bat face than in insolitiiin, while the sides are less convex. Also in stapes the rate of increase 

 is smaller than in insolituin. 



60. Den hl /lil l/l paihyplcuruiii n. sp. PI. V, figs 21, 22. 



Stat. 208. 5°39'S., 122° 12' E. Banda Sea. 18S6 Metres. Solid green mud. 2 Spec. 

 Stat. 271. 5°46'.7S., 134° o' E. Arafura Sea. 1788 Metres. Bluish green mud of a uniform 



appearance. i Spec. 



Diagnosis. Shell very slender, moderately curved, smooth, white and brilliant, without 

 longitudinal sculpture; cylindrical, but the convex side is very slightly laterally ƒ=^ 



compressed reminding one of forms like stapes and insolitiun. A transverse ll^_^ 



section near the apex shows that the wall on the concave curve is thickened, pjg 26. 



which is also the case in the preceding species; there is however not the faintest Section near the apex 



r !s r 1 oi D. pachyplcuriim. 



tracé of longitudinal angularity. Apex thick-edged with a supplemental tube. 

 Growth striae hardly noticeable. Anterior aperture subcircular, thin-edged. 

 Length 46 mill., greatest diam. 2,4 mill. 

 Length 36 mill., greatest diam. 1,9 mill. 



61. Dentaliiiiit friincafm/i n. sp. PI. VI, fig. 



o j- 



Stat. 90. 1° I7'.5 N., 118° 53' E. Celebes Sea. 281 Metres. Coral sand and stones. i Spec. 

 Stat. 256. s°26'.6S., 132° 32'. 5 E. Arafura Sea. 397 Metres. Greyish green mud. 2 Spec. 



Diagnosis. Shell slightly but evenly curved, cylindrical or faintly trigonally compressed 

 in the way of insolitiiiii. White and brilliant, nearly smooth but for some deeply ^r-^ 



incised wrinkles near the apex. Apex faintly trigonal, strongly truncated, thick- 4^gJ 



edeed with a minute orifice and a short supplemental tube. Anterior aperture 



'^ Fig. 27. .^pex 



subcircular, thin-edged, a little oblique. oi d. trunaunm. 



Length 18 mill., diam. of anterior apert. 1,5 of apex 1,4 mill. 



Length 16 mill., diam. of anterior apert. 1,6 of apex 1,1 mill. 



Length 23 mill., diam. of anterior apert. 2,3 of apex 1,4 mill. 



Remarks. All the specimens show deep irregular fissures where the shell after breakage 

 has been repaired. The concentric lines near the apex remind one of the group of D. tracheatimi. 

 The specimen of Stat. 90 has them over its whole surface while the others are anteriorly quite 

 smooth with superficial growth striae onl)-. 



Subgenus Laevidentalium Cossmann 1888. 



1888. Laevidentaliian Cossmann, Ann. de la Soc. Roy. Malac. de Belgique, XXIII, p. 9. 

 1897. Laevidentalium Cossmann. PiLSBRV & Sll.VRP, Man. of Conch., vol. XVII, p. 97. 



Shell of moderate or large .size, smooth, with growth lines only, circular or slighdy oval in 

 section ; apex simple (typically), or with a short notch on the convex side as in Antalis. (P. & Sh.). 



