P. N. Bose—History of the Extinct Carnivora. 271 
have been derived chiefly from organic life, in a quiet and somewhat 
deeper sea. The condition of the rocks composing the floor at the 
time is clearly indicated in the fragments plentifully found in the 
newer deposits. These show clearly that when broken off the rocks 
must have been not only indurated but crystalline, and that since 
that time little, if any, further change has taken place in them. 
The faults which occur are mainly in two directions, viz. from 
N.E. to 8.W. and from N.W. to S.E., and the lochs, lakes, and valleys 
usually follow the lines of these faults. Probably the main anti- 
clinal axis of the old rocks in the neighbourhood under consideration 
occurs nearly in the line of Loch Maree. The deeper beds being 
found along both sides of that lake, and the higher at Ben Fin and 
Mulart on the one side; and about Gaerloch on the other. Numerous 
minor folds of course are seen, but this seems to be the main one. 
The petrological evidence tends further to show that the newer 
rocks, even when partially altered by contact with intrusive rocks, 
or otherwise, never properly assume the character of the old rocks, 
and that the difference between them is easily recognizable under the 
microscope. 
In addition, evidences of an entire discordance in strike in the 
beds, and of having suffered very unequally from the physical 
changes which have affected the crust, are also usually most marked. 
In attempting to correlate the Pre-Cambrian rocks of these areas 
with those of Wales and elsewhere, we can at present only say 
definitely that the physical and mineral evidences tend to associate 
them with the Dimetian rocks. The thickness here is probably 
greater than in any area in Wales, and there is therefore a greater 
variability in their character. 
Whether they all belong to one conformable series is also a 
question of considerable importance. It may be that in the centre of 
the axis along Loch Maree an older formation is found than at the 
other points mentioned. We may here have the Lewisian exposed, 
and a gradual passage between the two formations; whilst on the 
other hand it is not impossible that even here they may be uncon- 
formable, as in other areas, to one another. 
In conclusion it is perhaps even now not too much to say that the 
same general results met with here are not only likely to be obtained 
by explorations along other lines to the N. and §., but highly pro- 
bable from much of the evidence already accessible. 
V.—Nores on tHE History anpD ComparaTIvE ANATOMY OF THE 
Extinct CarNIVoRA. 
By P. N. Boss, B.Sc. (Lond.), F.G.S. 
(Continued from p. 207.) 
HE dentition of Gymnura, an existing Insectivorous Mammal, 
may with advantage be compared with that of the Eocene 
Carnivora. The dental formula of Gymnura is typical :— 
3-3 1-1 4-4 3-3 __ 
J shag Mm. ist lint 44, 
The only other existing Mammals which have 44 teeth are the 
