6i 



the much narrower umbilicus, by the direction of the lower row of tubercles, which in B. Chuni 

 are erect, and on the contrary straight or nearly declined in S. pagodiformis, and other characters 

 of less importance. 



Guttula n. gen. 



Shell small, conoidal, smooth, pearly, perforate, aperture rounded, with an angle at the 

 base, operculum few-whorled. 



It is chiefly on account of the peculiar radula, that I have located the only species in 

 a new genus-, conchologically it resembles Margarita, were it not for the angular aperture. It 

 may prove to be only a young shell, but a similar radula I have only found in what I describe 

 with some doubt as a Basilissa and in the type of that genus ; however the differences of the 

 radulae are too obvious, to join them in one genus. 



i. Guttula sibogae n. sp. PI. II, fig. 7; PI. IX, iïg. 11. 

 Stat. 178. 2°4o'S., i38°37'.sE. 835 M. Blue mud. 4 Spec. 



Shell conoidal with elevated spire, periphery and base roundecl, perforate, pearly, outer 

 layer, if present, very thin and pellucid. Whorls 5, very convex, smooth, only under a strong 

 lens very faint growth-striae and microscopic punctuations may be observed, sutures well-marked, 

 marginated, last whorl rounded, with a convex base and a small perforation, nearly concealed 

 by the columella. Aperture rounded, slightly angular above and stronger so below, outer margin 

 thin, regularly curved, columellar margin concave, reflected over the small umbilicus, angular 

 near the base, where it joins the basal margin, and slightly protracted there. Operculum thin, 

 horny, with few whorls, concave at the outer side. 



Alt. 5 1 /., diam. maj. 4 1 /., apert. alt. 3 1 /,, lat. 2 s / 4 Mill. 



The radula has scarcely the length of 1 Mill. and is about '/.. Mill. in breadth; it has 

 about 20 transverse rows of teeth ; the rhachidian tooth (R) is broad, depressed quadrangular 

 with rounded upper angles and pointed basal ones, it has a large reflected cusp with one strong 

 median denticle and two smaller ones on each side, the laterals (1), one on each side, have a 

 depressed rhombic base, with a reflected margin, ending in a sharp cusp at the proximal side. 

 The other teeth (U) have the characters of being uncini, they are long, slender and hooked, 

 with apparently smooth cusps, the outer ones are shorter broader, with a few denticles on each 

 side, near the top, visible if expanded. The number of uncini is not large, but I could not 

 ascertain the exact number. 



Basilissa Watson. Fig. 1. 



To the kindness of Prof. H. M. Gwatkix, I owe the knowledge of the radula of the 

 type of the genus Basilissa lampra YVats. from a specimen of the original lot, collected off 

 Jedo, at 1875 fathoms. This radula has a very peculiar appearance, which is quite different 

 from that of the species located by v. Martexs in this genus, and which I have united, with 



61 



