apex, increasing toward aperture to about 40 and becoming gradually broader and stronger. 



Intervals at the top wide and rather flat, concave and narrower than 



the ribs at the anterior aiaerture. Ribs rather strong, well rounded and 



shining, equal in size, here and there alternating with some smaller ones. 



Apex circular with strong walls and a moderately deep slit. Anterior 



aperture rounded rather oblique with strong edges. 



Colour grayish white or with a yellowish tint. 

 Length 45, diam. of aperture 5,9 mill. 

 Length 47, diam. of aperture 6 mill. ^'s- "^- ^°'"'°'' ^'P^''"'"^ 



35. Dentalmm sedcciincostatitin n. sp. PI. VI, figs 8 — 11. 



Stat. 45. 7°24'S., ii8°i5'.2E. 794 Metres. Fine grey mud, with some radiolariae and 



diatomes. i Spec. 



9° 3.45., 1 19° 56.7 E. 959 Metres. Globigerina ooze. 9 Spec. 



0°34'.6N., 119° 8'.5 E. 1301 Metres. Fine grey mud. i Spec. 



0°29'.2S., 130° 5 -3 E. 469 Metres. Coarse sand and broken shells, i Spec. 



2°4o'S., 128° 37'. 5 E. 835 Metres. Blue mud. i Spec. 



5°44'.7S., I26°27'.3E. 4391 Metres. Dark mud. i Spec. 



4°24'.3S., 1 29° 49'. 3 E. 1570 Metres. Dark sand with small stones. A fragment. 

 Stat. 300. io°48'.6S., I23°23'.i E. 918 Metres. Fine grey mud. 9 Spec. 

 Stat. 314. 7° 36' S., II7°30'.8E. 694 Metres. Fine sandy mud. i Spec. 



Diagnosis. Shell slightly dorso-ventrally compressed, moderately curved, white porcel- 

 lanous, shining, sometimes chalky; often with a black incrustation near the apex (generally 

 most of it on the concave side) and with light and dark brown patches, irregularly distributed 

 over the rest of the shell's surface. Sculpture: near the apex there are 16 narrow rounded 

 ribs, closer on the concave curve than on the convex curve and separated by wider intervals. 

 Anteriorly there arises in each interval a median thread; it arises earlier on the concave side 

 and soon equals in strength the primary ribs; on the convex curve it remains small. Anteriorly 

 the whole sculpture becomes subobsolete, old specimens being quite near the anterior aperture 

 nearly smooth. Growth striae numerous and close, obliquely crossing the longitudinal sculpture. 

 The apex in young specimens has a short wide slit, in older specimens it is entire, dorso- 

 ventrally compressed with thick walls, thickest on the concave margin. 



Anterior aperture very oblique, slightly dorso-ventrally compressed, with thin margin. 



a. Length 29, diam. at apert. 3 X 2,6, diam. at apex 0,3 mill. 



b. Length 38, diam. at apert. 3,4 X 3,2, diam. at apex 0,4 mill. 



c. Length 39, diam. at apert. 4 X 3,8, diam. at ape.x 1,1 mill. 



d. Length 45, diam. at apert. 4,2 X 4,1, diam. at apex 0,9 mill. 



(The lateral diameter is given first). 



36. DentaliiLDi conipressiusciilum n. sp. PI. VI, fig. 12. 



Stat. 241. 4°24'.3S., 1 29° 49'. 3 E. 1570 Metres. Dark sand with small stones, i Spec. 

 Diagnosis. Shell moderately curved, slightly dorso-ventrally compressed posteriorly, 



SIBOGA-EXPEDITIE I.IV. C 



