34 



the later half nearly cylindrical ; slender, rather fragile, of a dirty yellowish colour. Sculpture 

 of 1 6 narrow rounded ribs at apex, increasing by intercalation of secondary riblets to the 

 number of 32 at about the middle of the shell's length, the riblets on the concave curve 

 appearing first. Lower down tertiary riblets arise, but only on the concave curve making 

 together a number of 48 equal narrow rounded riblets at the anterior aperture. Apex with a 

 slight notch on the convex side. Anterior aperture subcircular, a little oblique, acutely edged. 

 Length 31,5 mill., diam. of aperture 2,8 mill. 



37. Dentalium Martensi n. sp. PI. IV, fig. 19. PI. V, fig. i — 3. 



Stat. 88. o°34'.6N., 119° 8'.5 E. 1301 Metres. Fine grey mud. 5 Spec. and some fragments. 

 Stat. 223. 5°44'.7 S., I26°27'.3E. 4391 Metres. Brown and black mud gradually changing 



into bkiish grey mud. A fragment. 



Diagnosis. Shell near the apex a little dorso-ventrally compressed, more rounded 

 toward the anterior aperture; nearly straight or with a slight curve at the top. Sculpture of 



about 16 sharp cancellated longitudinal ribs, separated by wide plano- 

 concave intervals. Early on the concave side there appears in each interval 

 one interstitial riblet, soon equalling the first in size ; some tertiary threads 

 sometimes arise near the aperture. On the convex side the interstitial 

 riblets appear later and generally remain smaller than the ribs. The ribs 

 are finely cancellated with very irregular little rounded teeth. The sharp 

 p. . , . , edges of the ribs often are worn off by erosion. The intervals are trans- 



rig. 20. Antenor apevture ö -' 



of D. Martensi. versely striatcd but not conspicuously so, being in some shells smooth 



with hardly any indication of transverse sculpture. Apex dorso-ventrally compressed, entire with 

 an oval opening, or with a moderately long rather wide slit on the convex side. Anterior 

 aperture nearly circular a little dorso-ventrally compressed. 

 Length 56, diam. of apert. 6,3 X 6, of apex 1,7 mill. 

 Length 54, diam. of apert. 5,5 X 4,9, of apex 0,7 mill. 

 Length 41, diam. of apert. 5,1 X 5, of apex 1,8 mill. 

 (The lateral diameter is given first). 



*38. Dentalinin chithratiim v. Martens. PI. III, fig. 53. 



1881. DcntaUuiii clathratiiiii E. von Martens, Sitzungsber. der Gesellsch. naturf. Fr. zu Berlin, 



Jahrg. 1881, p. 66. 

 1897. Dentaliutn clathratiiiii E. von Martens. PiLSBRY & Sharp, Man. of Conch., vok XVII, p. 84. 



Diagnosis. Shell rather straight, elliptical in section, white, opaque, with about 16 

 angular, narrow, equal ribs, with smaller ones sparsely intercalated towards the aperture, the 

 interstices conspicuously transversely striated. Apical orifice thick-edged; slit on the convex side, 

 narrow, long. Length 51, transverse diam. of aperture 4, dorso-ventral diam. 3V3 mill., diam. 

 of apex "/a mill. (Mart. from I'. & Sa.). 



Distribu tion. Near Moreton Bay, Eastern Australia, 550 fms. (Gazelle Exp.). 



