TROCHUS. 23 



The figure given by Reeve, (f. 18) differs from specimens from 

 the Philippines before me in having the nodes vaulted on the lower 

 whorl. Upon all the specimens I have seen, the upper nodes only 

 are vaulted, the lower ones are solid, as in the following species. 



From T.. dentatus, the greater number and smaller size of the 

 peripheral tubercles with separate this species. The proportions 

 are different, too ; noduliferus being broader at the base. 



T. MAURITIANUS Gmelin. PI. 4, figs. 24, 25, 27 ; pi. 2, figs. 11, 12. 



Shell imperforate, conical, solid, marbled and maculated with 

 green, brown and rose-color on a whitish ground; whorls 10-12, 

 planulate, bearing vaulted or solid tubercles which project at the 

 sutures and upon the periphery of the last whorl, where they num- 

 ber about 16 ; whorls covered with oblique small folds, so interrupt- 

 ed as to appear more or less in spiral series ; base flat, white and 

 yellowish, unicolored, all over concentrically lirate, the line smooth, 

 narrow, separated by shallow grooves as wide or wider than the 

 ridges, and continuous within the aperture upon the parietal wall ; 

 aperture transverse, the outer wall lirate within, the basal margin 

 straight, bearing, within, a strong acute revolving lamella, opposite 

 to a similar but smaller one upon the parietal wall ; columella 

 short, with a very strong acute median spiral fold. 



Alt. 40-60, diam. 40-55 mill. 

 Indian 0., Madagascar, Seychelles, Red Sea (Jonas) Philippines. 



T. mauritianus GMEL., Syst. Nat., xiii, p. 3582, 1788. Tectus 

 pagodalis MONTFORT, Conch. Syst. ii, p. 187, 1810. T. costifer 

 JONAS, Zeitschr. f. Mai, 1846, p. 123. PHILIPPI Conchy I- Cab., p. 

 .113, t. 19, f. 1; t. 41, f. 9. 



The above description applies to the typical form of this species, 

 the prominent characters of which are the smooth, subequal basal 

 lirse, closely wrinkled upper surface, with projecting peripheral tu- 

 bercles, and strongly uni-lamellar basal and parietal walls of the 

 aperture. I have not examined enough specimens to say with any 

 degree of certainty how constant these characters will prove to be. 

 I observe considerable variation in the sculpture of the aperture in- 

 side in the species of this group ; the lira? being sometimes complete- 

 ly absent in species which normally possess them. Whether the 

 same variations attend the strong lamellae of the present species, I 

 cannot say. 



