152 Gr- Nevill— New or little-hnoicn [No. 3, 



var. sublaevis, nov. 



The spiral and longitudinal striation more or less obsolete, Mauritius. 



TSpe var. Indian Museum ; also in coll. Caldwell. 



var. sexcaeinata, nov., PL VI, Fig. 10 A. 



A very handsome, solid form, with six prominent keels on the last 

 whorl, the interstitional striation obsolete, as in the preceding variety, 

 columellar margin subangulately rounded, instead of oblique. 



Alt. 34, diam. 35^ mil. — Mauritius. 



Type var. Indian Museum ; also in coll. J. Caldwell. 



I may take this opportunity of recording that Mr. Caldwell possesses 

 a variety of G. carinatum with four keels. 



Ctclostoma (Teopidophoea) eeeoneum, n. sp. 

 Pfeiffer, Conch.-Cab. II, pi. 39 figs. 5—7, Locality (?), as C. unicolor (not C. 

 unicolor, Pfr., P. Z. S. 1851, or of Reeve fig. 39). 



I take as my type, the abundant form represented by Pfeiffer' s above 

 quoted fig. 7 ; the larger variety seems to be much rarer. Though exceed- 

 ingly variable, G. erroneum can always be easily distinguished from G. 

 carinatum and its variety, the " unicolor'" of Pfeiffer 1851 and of Reeve, 

 by the regular and close-set spiral sulcation, without the prominent and 

 characteristic keels of its ally ; though more or less subangulate at the 

 periphery, the whorls are always more convex, and this is esj>ecially 

 noticeable at the base of the last whorl, which is also spirally sulcated, 

 instead of being smooth as in G. carinatum and as well shown in Reeve's 

 figure of Cuming's type of G. unicolor ; the umbilicus is always markedly 

 less open, as well shown in Pfeiffer's fig. 6. 

 Type, Indian Museum. 

 Alt. 21|, diam. 24 mil. 



Keel round the umbilicus almost or altogether obsolete. 

 M. Morelet in the Journ. de Conch, for 1877, p. 213, describes and 

 separates under three " heads," the forms figured by Reeve and Pfeiffer, &e. 

 which he unites as varieties of C. unicolor ; if this be done, I consider it 

 impossible to avoid uniting both to G. carinatum, from which the type of G. 

 unicolor differs less than does the latter from my G. erroneum. Undoubt- 

 edly we have here an instance of a gradual transition from the extreme 

 form of G. carinatum to the G. unicolor, var. G. of Morelet, intermediate 

 forms of countless variability having been preserved for us in a subfossil 

 state. It is, I think, comparatively immaterial whether we consider G. 

 carinatum, unicolor, and erroneum as distinct species, or the two latter as 

 subspecies of the first ; after a careful examination of many hundreds 

 of specimens, I think it better not to separate the true G. unicolor from C. 

 carinatum, except as a variet}^ and preferable to separate the (more or less) 



