42 



stitial striation, which lacks in D. dipsycha and by the greater rate of increase of D. tetrapleurum 

 which is altogether a more robust shell. 



The South American D. quadrangulare agrees with fetrapleurjiin in having longitudinally 

 striated interstices. Here however no secondary and tertiary riblets appear, while its rate of 

 increase is still greater than in our species. 



50. Dcntaliiiin guadrapica/c Hanley. PI. I, fig. 13. 



i860. Dcntalium quadrapicale Hanley MS. Sowerby, Thes. Conch. Ill, p. 103, pi. 225, fig. 61. 



1872. Dcntaliiiiu qiiadrapicale Hanley, Conch. Icon. pi. 7, fig. 46. 



? Dentalium qiiadrapicale Hanley. Clessin, Conch. Cab. p. 13. 



1897. Dentalium qiiadrapicale Hanley. PlLSURY & Sh.\RP, i\lanual of Conch., vol. XVH, p. 34, 

 pl. 4, fig. 50. 



Stat. 51. Madura bay and other localities in the southern part of Molo Strait, i Spec. 



Diagnosis. .Shell rather stout, apical third strongly curved, the remainder but slightly 

 arcuate; white, shining. Sculpture: four angles at the apex (giving that part an almost square 

 section, the two outer sides of the square slightly longer), situated at the outer, inner and lateral 

 surfaces, the faces between them straight and flat; these angles rapidly lose in prominence, and 

 the intervals become convex; very near the apex each interval becomes parted by a secondary 

 riblet; and the interstices between these are again divided by tertiary threads at about the end 

 of the first third of the shell's length; and subdivision proceeds until at the aperture there are 

 about 36 low, subequal riblets, with narrow, shallow intervals, and the tube is subcircular, a 

 little flattened antero-posteriorly, in section. Growth striae faint. Aperture very oblique. Anal 

 orifice without slit or notch. 



Length 20, length of aperture, measured obliquely 3V3, breadth 3 mill. 

 Length 31,5 mill, (original fig.) (P. & Sh.). 

 Length 40 mill, (reported by E. A. Smith). 



Distribution. Cochin; Malabar (H.\nley Coll.). Coast of Travancore. 406 fms (Investi- 

 gator) ; Gulf of Oman (Melv. & St.\nden). 



The following is probably a description of an old specimen of D. qiiadrapicale Hanley. 



Dentalium conspictnim Melvill. PI. II, fig. 26. 



1897. Dentalium conspicuum Melvill., Mem. and Proc. Manchester Lit. and Phil. Soc, XII, 



pt 3, p. 21, pl. 7, fig. 28. 

 1897. Dentalium conspicuum Melvill. PiLSBRV & Sharp, Man. of Conch, vol. XVII, p. 248, 



pl. 33, fig. 60. 



Shell shining, subulate, arcuate, milk-white, longitudinally delicately striated, the striae 

 unequal, here thin and there thicker, spirally irregularly concentrically encircled by lirae ; at the 

 ape.x octagonal, toward base vanishing, the base itself very smooth, rotund. 

 Length 1^/4, diam. 'Vi^ inch. (Melv.). 



Karachi. 



