1888-89.] Mr G. Brook on Homologies of the Mesenteries. 39 
(after the formation of the first twelve mesenteries) to two mesen- 
teries instead of one, the Hesactinian type is reached. In certain 
Madreporaria (e.g., Lophohelia , Mussa , and Euphyllia) the radiate 
arrangement appears never to he lost. At any rate, according to 
Fowler and Bourne, there are no mesenteries distinguishable from 
the others as “directives,” and there is a perfectly radiate sym- 
metry. 
Such a general plan of development in the Anthozoa is found in 
another form, for instance, in Peripatus and Vertebrata. In Peri- 
patus the blastopore becomes elongate, and closes in the centre, but 
its two extremities remain open, as the mouth and anus. The 
mesoblastic somites are formed in the region in which the blastopore 
has closed, and these become more numerous as the two extremities 
become more and more separated. At present I am only able to 
indicate the bearing of these views in outline. I hope, however, 
shortly to make a more detailed communication on the subject. 
On Certain Bodies, apparently of Organic Origin, from 
a Quartzite Bed near Inveraray. By His Grace The 
Duke of Argyll, K.G., K.T. 
(Read January 14, 1889.) 
The magnificent sections of the Archaean and Pakeozoic rocks 
which are presented on the north-west coast of Scotland, have 
long been known to all British geologists. They occur principally 
in the counties of Sutherland and Wester Ross, from Cape Wrath 
on the north to Loch Kishorn on the south. They are not less 
striking in an artistic, than they are instructive in a scientific 
point of view. The height of the mountains, their abrupt and 
precipitous forms, and the thinness, or almost total absence of, 
superficial covering, are characteristics which combine with great 
variety and richness of colouring, to produce scenery which stands 
altogether by itself. The great rock masses to which its peculi- 
arities are due are principally three, differing widely in geological 
age, in composition, and in texture, and yet often so piled upon 
the top of each other that very often one single landscape, and 
