460 
Linncean Society. 
the Helices. 'J’he author gives moderately long and complete com- 
parative descriptions of 3 species of Anostoma, 2 Tomigerus, 24 Stre- 
ptaxis, Q Proserpina, and 1148 species of Helix, with their synonyma 
most carefully and completely elucidated. It forms one of the most 
important additions which have lately been made to the study of 
shells. 
Malacologically considered, the work must be regarded as a retro- 
grade movement : the author is a pure conchologist, belonging to the 
same school as Klein, Montfort and Schumacher, for he pays little or 
no attention to the animal, and even refuses to adopt genera formed 
on the study of them : if the same system was followed with regard 
to the marine mollusca, several groups which are now considered as 
families, each containing several generally adopted genera, must be 
reduced to a single genus. In the same manner, the immense num- 
ber of kinds of Helices are arranged together in an artificial manner, 
without any attention to their relation to one another, which is more 
to be regretted, as Ferussac in his ‘ Prodromus’ arranged the species 
which he knew in most excellent natural groups ; but Dr. Pfeiffer 
appears to be quite destitute of the faculty of distinguishing or cha- 
racterizing natural groups, though he describes the species so well. 
It was the remarkable union of these qualities in the same individual 
which so eminently distinguished Linnaeus, Jussieu and Lamarck 
from other naturalists, and causes the great value of their works. 
A large proportion of the species are described from the English 
collections, and where the author has not observed the species him- 
self, he quotes descriptions given by its original describers. 
PROCEEDINGS OF LEARNED SOCIETIES. 
LINN^AN SOCIETY. 
Feb. 15, 1848. — The Lord Bishop of Norwich, President, in the Chair. 
Read a memoir “ On the early stages of the Development of Le- 
manea jiuviatilis, Agardh.” By G. H. K. Thwaites, Esq. Commu- 
nicated by the Rev. M. J. Berkeley, F.L.S. 
Mr. Thwaites attributes the neglect of the early condition of this 
conferva to its having been confounded in this stage with Trente- 
pohlia pulchella /3. cJicdyhea, Harv., with which it is frequently found 
growing intermingled. He states that it may be observed in great 
abundance towards the end of November, covering the surface of 
stones with a uniform, dark olive, somewhat villous coating, and 
adhering with great pertinacity by means of its minute roots. The 
structure of the plant at this early stage is found to consist of nu- 
merous conferva-like filaments, of about a line in length and spa- 
ringly branched. Each filament is about y ^^q^ th of an inch in dia- 
meter, and consists of a single row of cells, which are from 4 to 6 
times longer than wide, and have a blue-green endochrome arranged 
