xi 
uninterruptedly from the north-east, with an occasional storm from the 
south; and he was willing to admit that these storms might possibly 
account for the slight African element in the fauna; but the large number 
of Mediterranean types could not, in his opinion, have originated from 
atmospheric causes. Floating timber, and human agency, especially the 
introduction of plants from Europe, and from one island into another, no 
doubt played a not inconsiderable part both in the character of the fauna as 
a whole and in its details. 
A lengthened discussion followed the reading of this paper, in which the 
President, Mr. Bates and Mr. Murray, who was present as a visitor, took 
part. 
Mr. Bates considered that Mr. Wollaston had adduced no new facts 
calculated to convert those who do not believe that the present community 
of species in these islands is to be explained by former land-connection, 
inter se, and with south-western Europe. Mr. Wollaston had not endea- 
voured to meet the objection to his theory, raised by Sir C. Lyell in his 
‘Principles of Geology,’ viz., that the Atlantic Islands, and especially the 
Azores, are separated from the continent of Europe by a sea of from 10,000 
to 15,000 feet in depth. It was pretty generally acknowledged that all 
great geological changes were extremely slow in their operation, and this 
being the case, a land-depression of that magnitude must have occupied a 
length of time that could only be measured by geological epochs; in fact, 
would throw back the operation to a period probably prior to the origin of 
the now existing insect fauna of the islands. It was not in accordance with 
the present state of Science to call to our aid the idea of “ great catas- 
trophes,” or if that course be adopted, we should be prepared with facts 
in support of the theory. 
Mr. Murray agreed with Mr. Bates with regard to his remarks on “ great 
catastrophes,” and thought Mr. Wollaston in that respect had chosen a 
wrong position; but he did not agree with him in his estimate of the length 
of time necessary for the operation of great geological changes. Fossil 
shells, &c., from Solenhofen were referrible to recent genera, and Prof. 
Heer had identified the fossil plants of the miocene of Madeira with genera 
now existing there. Furthermore, it was known that Cardium edule was 
found in a fossil state in the Aralo-Caspian region and in the Sahara, and 
he thought the elevation demonstrated by this fact was not opposed to the 
idea of a corresponding depression in the Atlantic. The great objection to 
his mind, to the theory of population by atmospheric means, was the 
remarkable homogeneity of form in the fauna of the various groups. If the 
fauna were derived from atmospheric agencies there would not be this 
community of form. As a proof of this he would cite Keeling Island, 
which has an insect-fauna of nineteen species, belonging to almost as many 
orders, 
