Cretaceous Gastropoda, and Pelecypoda from Ziduland. 49 
parallel to each other until they unite in a gentle upward curvature 
to form the inner margin of the flat dental plate extending from the 
base of the ligament region. The interior of one of the fragments 
also shows obscure evidence of a third dental ridge produced by a 
bifurcation, about half-way, of the lowest ridge and parallel to it ; 
grooves of corresponding length accompany the ridges on each 
side, the central one being the deepest and most prominent. In 
more perfect specimens further dental ridges should be seen at the 
posterior angle, but as only about five ligament pits are present 
instead of probably double that number it follows that only little 
more than half the maximum length of the hinge-plate is preserved. 
Unfortunately the umbones also are not present, so that it is impos- 
sible to say how far the valves extended anteriorly, but from com- 
parison with other specimens that extension would have been 
extremely small. As with most forms of this genus, the left valve 
shows the greatest convexity, the other being appreciably com- 
pressed. The anterior parts of the valves exhibit externally a 
sub- cylindrical contour with a deep, abrupt, and gently concave 
ventral region, whilst the dorsal surface is compressed, oblique, and 
triangulate, thus entering into the formation of the posterior expan- 
sion. One of the fragments represents the central region of a left 
valve, showing its median convexity and well-sloping sides, the 
ventral margin being well rounded, and the opposite margin being 
either straight or slightly concave. The outer surfaces of the 
specimens are furnished with somewhat coarse, oval growth-lines, 
which agree in every way with the normal ornamentation of this 
species. 
Such characters as are here notified are generally to be met with 
in good specimens of the species from either Blackdown or Ather- 
field, and it does not seem possible to refer the remains from 
Zululand to any other form. To Mr. H. Woods we are indebted 
for the latest account of this mollusc, its comparison with allied 
forms being ably worked out by that author. 
The late Dr. Stoliczka, who had seen no Cretaceous form of 
Gervillia from Southern India, refers to the fact that Orbigny had 
described and figured G. solenoides of Defrance as occurring in the 
rocks of Pondicherry (Cretaceous Pelecypoda, Southern India, 
Pal. Indica, 1871, pi. 50, fig. 5, p. 409). 
With regard to African examples of Cretaceous GervillicB, there 
is only one which need be compared to the present shell, and 
that is G. dentata of Krauss {Nov. Act. Acad. Gees. Leop. -Carol. 
Nat. Cicriosorum, 1850, vol. 22, part 2, pi. 50, fig. 1, p. 458), from the 
Uitenhage deposits (Lower Cretaceous) of South Africa, a shell, 
4 
