60 Proceedings of Royal Society of Edinburgh. [sess. 
much denuded, it is evident that the exterior was marked by lines 
of growth, which are much stronger at regular intervals of about 
J inch, giving a ringed appearance to the shell. Below some of 
these lines, especially towards the margin, the surface is puckered 
by vertical ridges, which give the shell an indistinct frilled appear- 
ance, like that seen on some examples of C. planata from the 
Thanet Sands. The almost equilateral form and nearly central 
umbones serve to distinguish this fossil from any shell which has 
been referred to the genus Cyjorina ; and the form which comes 
nearest to it is one from Navidad, Chili, described by Sowerby in 
Darwin's Geological Observations in South America (1846, p. 250, 
PI. II. fig. 11) as Corbis (?) laevigata. The original specimen of 
this species is preserved in the Natural History Museum at South 
Kensington, and has been compared with the present fossil. It 
seems highly probable that the two shells may belong to the same 
genus, and this, as we think, is most likely to be Cyprina. 
Although the two shells are in many respects very similar, our 
Antarctic specimen has less inflated umbones ; its greatest thick- 
ness is about the middle of the valves, and when complete was a 
rounder shell. In C. laevigata the valves are more inflated, and 
this chiefly towards the umbonal region, while it is a wider and 
more oval shell. These differences seem too great for specific 
identity, and, seeing how much we are indebted to Captain Larsen 
for the preservation of these fossils, we suggest that his name be 
associated with it and that it be called Cyprina Larseni. 
The specimens of wood are very similar to that noticed in our 
previous paper, and sections prepared from some of them show that 
they also are coniferous ; indeed, there is no reason why they should 
not all have been taken from one log. 
Examples of the matrix found attached to the outside of this 
wood have also been received, and are found to be a calcareous grit, 
similar to that filling the mollusc shells, and it is highly probable 
that they come from the same formation. Mr J. J. H. Teall has 
examined this matrix, and says: “It is composed of angular frag- 
ments of quartz with minute particles of garnets, muscovite, and 
other minerals, cemented by carbonate of lime.” Several pieces of 
this wood have been riddled by some boring animal, probably 
Teredo , or an allied form ; sometimes the tubes are isolated, but in 
