T. H. Withers—Pollicipes levis, Shy. 495 
Taste XVII (continued). 
Matope, Cuyuni Berbice 
(red). (white). 
Quartz é =a 6:8 
Colloid Silica “4 “3 
Orthoclase 1:2 1:9 
Plagioclase . 8 3 
Kaolinite 45°5 76°3 
Tale DOF “4. 
*+Bauxite 4+4 6°5 
Ilmenite 1:9 7:4 
Hematite 19 
Limonite ; 2 ; P 24-2 traces 
Minor constituents : : : oil 
100°2 100 
*Gibbsite F 4 : F : 4-4, 6°5 
ft Total Alumina present in Bauxite . 2-9 4:2 
The cementing material of these rocks is kaolinite with varying 
proportions of felspathic rock powder and perhaps some bauxite. 
The contents of the spheroids in the red’ one from the Cuyuni is 
presumably a mixture of oxide and hydrate of iron, of which con- 
stituents the rock contains over 40 per cent. In the white one 
from the Berbice River both spheroids and cementing material appear 
to consist mainly of kaolinite with some bauxite. In their com- 
positions the rocks offer little resemblance to those of the two 
varieties of purely ferruginous and purely aluminous laterite described 
by Du Bois which they so very closely resemble in other respects. 
(Lo.be concluded in the December Number.) 
TV.—Tue Cretaceous CrreiPeDE PoLLicrPes L&VIS, J. DE C. Sowersy. 
By Tuomas H. Wiruers. 
DE C. SOWERBY (1886, p. 335) founded two new species of 
» Pollicipes from the Gault of Folkestone. To the one, based 
on a carina and tergum, he gave the name P. levis (p. 335, pl. x1, 
fig. 5); to the other, based on a rostrum and one of the latera of the 
lower whorl, the name P. wngwis (p. 335, pl. x1, fig. 5*). He also 
referred a carina and tergum from the Upper Greensand of Blackdown 
to P. levis (p. 340, pl. xvi, fig. 1), but published no description 
of them. 
J. Steenstrup (1837, p. 363) founded the species P. elongatus on 
a scutum and tergum from the Danian of Denmark, but later (1839, 
p- 409, pl. v, figs. 7-11, 7*) referred the type-specimens, with other 
valves, to Sowerby’s P. levis. 
Subsequently, C. Darwin (1851, p. 55) maintained the species 
P. elongatus, at least for the scutum, and (p. 65) recognizing 
that the valves from the Gault of Folkestone described by Sowerby 
under the names P. levis and P. unguis represented a single species, 
thought it advisable to adopt for it Sowerby’s name of P. unguis, 
especially as Steenstrup (1839) had described valves belonging to 
different species under Sowerby’s name P. levis. 
The valves from the Upper Greensand of Blackdown remain to be 
considered. 
