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TRANSACTIONS OF THE SECTIONS. ‘65 
15th of June instant this remarkable sound. It is probable the sound is only emitted 
by*the male: it‘has as yet only been heard in the months of May and June. 
On a New Genus of Mollusca Nudibranchiata. 
By Messrs. AupER and Hancock. 
This new genus is founded on the Tritonia arborescens of authors and its allies, 
which are, distinguished from the true Tritoniz (Z. Hombergii, &c.) by the form of 
their tentacula, and the free, arborescent nature of their branchiz. ‘Uhese characters 
alone induced the authors to consider them generically distinct, before they had an 
opportunity of examining their internal structure, in which such important differences 
in the digestive organs were exhibited as to show that this‘new genus, for which the 
name of Dendronotus is proposed, should be removed from the family Tritoniade to 
that of Eolidide, to be placed first in order, as the connecting link between these two 
families. 
The paper was illustrated by drawings from the work by Messrs. Alder and Han- 
— 
- cock on the British Nudibranchiate Mollusca, just published by the Ray Society, 
Mr. W. Thompson read a letter from Mr. Alder, dated Salcombe, June 17, 1845, 
in which the writer stated that he had lately obtained in Torbay at least ten, and 
perhaps twelve new species of Mollusca nudibranchiata, to add to the British Fauna, 
They consist of four species of Doris, five or six of Zolis, and an animal of an entirely 
new genus, approaching nearest to 7ritonia. A singular species of mollusk obtained 
at the same time, resembling in general appearance the genus Pelta of Quatrefages, 
was noticed in detail. 
A letter was read by the Secretary from Captain Portlock, replying to the remarks 
made at York by Professor E. Forbes on the results of his dredging at Corfu. The 
account then read he had not wished to be considered a complete report, but as an 
indication of progress. In conclusion, Captain Portlock stated, that ‘in dredging, a 
conclusion from a very limited range of research is as dangerous as similar conclusions 
have been in geological inquiries. For example, a hasty deduction from the appear- 
ance of an animal at a particular depth of water is evidently imperfect, as the nature 
of the bottom and the description of the marine vegetation are more likely to modify 
such appearances, I see, for example, that Professor Bell quotes the discovery of 
Eurynome aspera by Professor Forbes in the deep water of the Egean as a proof that 
the species is essentially a deep-water one, both in the Mediterranean and the Northern 
Seas. Here, however, I have found it just at the verge of the rocks where sea-weeds 
prevail, and therefore in comparatively shallow waters, i. e. from ten to sixteen fathoms. 
Other northern species, such as Ebalia Pennantii, Acheus Crouchii (if I am right in 
my identification of them), I have found under similar circumstances; and I am, 
therefore, the more inclined to ascribe their existence to the local peculiarities of vege- 
_ tation than to the depth.” 
_ Professor Forbes exhibited a specimen of a Medusa, caught by Mr. M‘Andrew, and 
preserved in Goadby’s solution, and pointed out the importance of this means of pre- 
serving those soft animals. We know less of the Medusz than of any other family of 
animals, from the difficulty of preserving them, 
— —— 
On the Marine Fauna of Cornwall. By Cuartzes Wittiam Pracu. 
He introduced Natica intricata of Couch, Anatifa levis, A, suleata, A. fascicularis, 
and Pollicipes scalpellum, observing upon their habits, particularly the latter, showing 
that, notwithstanding it had been considered as solitary, he had found it in bunches 
of twelve or more in all stages of growth, and attached to the stems of the older ones, 
He then presented specimens of the Cineras vittata of Leach, which he took from the 
bottom of a vessel, timber laden, discharging at Plymouth from Africa, and then com- 
mented on the fact, that though this shell was a native of a warm climate, and was 
introduced into this country in the midst of the most severe winter experienced for 
1845. F 
a 
