446 Proceedings of the British Association. 



But not agreeing with the views of M. de Quatefages, they remained 

 content to consider the Mollusca Nudibranchiata as still forming one 

 entire group, divisible into two sections, distinguishable from each other 

 by external characters, and probably equally so by physiological pecu- 

 liarities, the limits of which have not yet been ascertained in the several 

 genera. These animals were much neglected till the time of Cuvier, who, 

 however, only dissected specimens preserved in spirits, and fell into 

 some errors. In Great Britain little was known till recently, but 

 through the researches of Prof. E. Forbes, Mr. W. Thompson, of Belfast, 

 and the authors, the species now amounted to seventy-five. The Report 

 then proceeds to examine the distribution of these seventy-five species, 

 which is a greater number than is given for any other part of the world, 

 on the coasts of the British islands. This is followed by an account of 

 their development, their minute structure, and a list of all the known 

 British species. 



Professor Allman mentioned a new genus, approximate to the genus 

 Venillia of Messrs. Alder and Hancock, which he obtained from a salt- 

 marsh in the south of Ireland. 



Report of the Dredging Committee for 1844. — This Report consisted 

 of two parts : 1st, of the records of a series of dredging operations 

 conducted round the coasts of Anglesea, in September 1844, by Mr. 

 M 'Andrew and Prof. E. Forbes, exhibiting the distribution of the 

 marine animals procured in various depths down to thirty fathoms, 

 and the state of the sea-bed in the localities explored. Among the more 

 interesting facts recorded in these papers were the following : rolled 

 specimens of Purpura lapillus, a shell which lives only above low-water 

 mark, were found in 28 to 30 fathoms water on the gravelly bed of 

 a line of current, at the distance of eight miles from the nearest shore. 

 In the same line of current it was found that the few mollusca which 

 lived there, such as Modiolae, and Limae, had constructed nests, or 

 protecting cases of pebbles, bound together by threads of byssus ; and 

 one species, the Modiola discrepans, had made its nest of the leaf-like 

 expansions of Fluslru foliacea cemented together. The attention of the 

 dredgers was directed, among other subjects, to the distribution of 

 Serpulse, and the results of their researches were confirmatory of the 

 statements recently advanced by Dr. Phillippi, of Cassel, namely, that 

 no dependence could be placed, even as to the genus, on the shell of a 

 serpula, perfectly similar shells being constructed by animals of different 

 genera. Thus they found all the serpulse of a particular form in 12 

 fathoms water to be a species of Eupomatus, whilst exactly similar shells 

 in 20 fathoms proved to be the habitations of a species of the genus 



