546 Meeting of the British Association. [ Oct., 
carotid, which crossed the wind-pipe to the left side. The second 
branch divided into the left carotid and descending aorta. With 
regard to the first example it had occasionally been met with by 
anatomists, but the second the author considered unique, the most 
experienced observers having failed to record anything similar. He 
considered this variation in the larger blood vessels as a deviation 
from the standard or well-recognized ordinary type, and to some 
extent a precursor of similar conditions in the lower animals. Their 
occurrence, however, could not be determined during life, nor could 
any special deduction at present be drawn from them. In the first 
example, the blood vessels of the extremities had become converted 
into what might be popularly called cylinders of bone, examples of 
which were submitted to the Section. Dr. Gibb also illustrated his 
paper by some well finished drawings. 
The papers bearing on the subject of Distribution were very 
numerous, but have very little interest at present in an isolated 
form, beyond the bare facts expressed in their titles. Mr. Gwyn 
Jeffreys read his report on dredging among the Hebrides ; while 
Mr. H. B. Brady furnished some remarks on the Rhizopod Fauna 
of those islands; Mr. G. 8. Brady reported on the Ostracoda; and 
the Rev. A. M. Norman gave a list of the Crustacea, Echinodermata, 
Polyzoa, and Ccelenterata of the same locality. Mr. John Shaw 
endeavoured to show, in a clever essay, how the distribution of 
mosses in Great Britain and Ireland was connected with the Geogra- 
phical and Geological history of the present Flora. The chief 
points touched on in the paper were of a geological character, such 
as the gradual glaciation from Miocene periods, breaks im the glacial 
period, the elevation of land as necessary for the existence of an 
Alpine, meridian, and southern flora contemporaneously. <A 
similar paper was that by Mr. Hennessy, F.R.S., on the probable 
cause of the existence of a north European flora im the west of 
Treland. Mr. John Hoge, F.RS., read a paper on the ballast 
flora of the coasts of Durham and Northumberland; and Mr. 
Moggridge noticed the occurrence of Lemna arrhiza in Epping 
Forest, and furnished a paper on the zones of the coniferee from the 
Mediterranean to the crest of the maritime Alps. Dr. Perceval 
Wright read some notes and exhibited specimens derived from a 
botanical tour in the islands of Arran, West of Ireland. 
Two papers were read in which the object of the author was to_ 
account for certain phenomena by the aid of the theory of natural 
selection, hence dealing with the “reason why” they would come 
under Professor Huxley’s definition of Physiology in its broad sense. 
One was a short note by Dr. Perceval Wright, on a moth, Lithosia 
cantola, which occurred in a single bay in the county of Dublin. - 
It had been supposed that this form was introduced by smuggling 
