20 TROCHUS. 



smooth, angulate at the periphery ; base flat, concentrically lirate, 

 the ribs smooth, wide, separated by shallow grooves, obsolete 

 toward the outer margin; aperture transverse, very oblique, sub- 

 triangular, the outer wall grooved within, the basal margin straight, 

 not concave in the middle, deeply notched at its junction with the 

 columella, sculpture inside with revolving acute plicae, corresponding 

 to the lirse which revolve around the central area outside ; columella 

 very short, with a very strong acutely carinated spiral fold. 



Alt. 75, diam. 75 mill. 



Indian and Pacific Oceans ; Samoan, Viti and Philippine Is., New 

 Caledonia; N. Australia, etc. Singapore (Archer.) 



T. obeliscus GMEL., Syst. Nat., xiii, p. 3579, 1788. T. pyramis 

 BORN, Test. Mus. Cces., 1780. T. pyramis PHIL., Conchyl. Cab. p. 

 2 Reeve, Conch Icon., f. 8. T. acutus LAM., An. sans Vert., 1822, 

 vii, p. 23. T. tabidus REEVE, Conch. Icon., f. 74. 



I believe that this is the T. pyramis of Born; but since there is 

 some doubt about it, I have followed the precedent of Dr. Fischer 

 in adopting Gmelin's name. T. acutus Lam. is an immature indi- 

 vidual, (pi. 2 fig. 13). 



Var. CCERULESCENS Lamarck. PI. 4, fig. 26. 



Form more slender than in the type ; spiral beading sub-obsolete; 

 color dark greenish, obliquely strigate with brown ; base green, brown 

 or yellowish ; outer wall of aperture (in the specimens I have seen) 

 not grooved within ; other characters as in the type. 



T. ccerulescens Lamarck, An. sans Vert., vii, 1822, p. 18. T. 

 prasinus Menke, Moll. Nov. Holl. Spec., p. 16, 1843. 



Var. TABIDUS Reeve. PI. 43, fig. 1. 



Whorls obliquely irregularly wrinkled, tubercled toward the apex; 

 base obsoletely grooved. Australia (Reeve). 



T. DENTATUS Forskal. PI. 3, fig. 23. 



Shell large, imperforate, conic-turreted, solid, heavy, grayish pink, 

 but unicolored and dull; whorls about 12, plan ul ate, more or less 

 obviously finely radiately wrinkled, often showing a few spiral rows 

 of beads, finely, very obliquely striate, but all this surface sculpture 

 often obsolescent ; periphery of whorls and at the sutures armed with 

 distant strong radiating solid knobs, about six to ten on the last 

 whorl; base flat, smooth, partly polished, with an appearance of 

 obsolete concentric lira? about the central portion, white, or with a 

 zone of blue or of green or both colors surrounding the axial tract ; 



