24 
no data supporting this, but he had neglected the experimental 
evidence to the contrary, which had been brought forward by Messrs. 
Merrifield and Poulton. He maintained that an agent was required to 
act on the larva physically, and produce variation, and that then 
“ natural selection ” was the all-important factor. Meteorological con¬ 
ditions offered such a primary agent—moisture and probably temperature 
being the most powerful factors, whilst smoke, probably, also acted 
constitutionally ; smoke and moisture also darkened objects, hence they 
acted indirectly as well, and in the direction of the production of melan¬ 
ism. Mr. Robson’s suggestions were entirely unable to meet very many 
common cases of melanism,where melanic and pale varieties occurred side 
by side, and where “ natural selection ” was clearly the essential factor. 
Dr. Chapman, who then spoke, considered that an exciting cause (or 
causes) was necessary to produce variation, and that “ natural selection ” 
was the means by which distinct races were then developed. A 
further animated discussion followed, the proceedings terminating with 
a vote of thanks (proposed by Mr. Tutt, and seconded by Dr. Buckell) 
to Mr. Robson, for his kindness in coming from Hartlepool to read the 
paper. 
Tuesday, 7 th March, 1893.—Exhibits :—Dr. Sequeira, Anisopteryx 
cescularia and Hyhernia leucophcearla, taken that day in Victoria Park. 
Mr. Battley, a living female of Nyssia hispidaria, from Epping Forest; 
also various fossil shells from the Red Crag at Felixstowe. He pointed 
out that the spiral shells were turned the opposite way to the forms 
now existing. Mr. Riches, shells of Helix virgata, H. ericetorum, H. 
cantiana, H. hortensis, H. nemoralis and H. aspersa. Mr. Clark, speci¬ 
mens of the Swan Mussel ( Anodonta ). Mr. Soul, very fine specimens 
of the Paper Nautilus ( Argonauta argo ) and Pearly Nautilus ( Nautilus 
pompilius). Mr. Rosevear, a selection of shells, to illustrate his paper. 
Mr. Bellamy, stuffed specimens of the Waxwing and Kestrel, from 
Yorkshire. Mr. Rosevear then read his paper on “ Concliology.” He 
claimed as advantages of this science, that it could be pursued at all 
times of the year, and in all weathers, that the specimens were easily 
preserved, and not liable to subsequent deterioration. He then pro- 
ceeded to give an outline of the structures, life histories, and habits of 
various mollusca, and closed by referring to the recently established 
Malaclialogical Society of London. Mr. Lewcock stated that the larvae 
of Hydrophilus piceus, fed on small water snails. He also jn’oposed a 
vote of thanks to Mr. Rosevear; this was seconded by Dr. Buckell, and 
carried. Mr. Riches stated that he had taken Biston hirtaria, on 
March 3rd. Mr. Lewcock also recorded this species. Mr. Battley 
remarked that the sallows were already coming into bloom, some of 
the sheltered bushes being fully out. 
Tuesday, 21 st March, 1893.— Exhibits: —Mr. Clark, Nyssia hispidaria, 
Phigalia pilosaria, etc., from Cliingford. Mr. Hollis, Phigalia pilosaria, 
Hyhernia leucophcearia and H. progemmaria, from Higligate,two females of 
the latter beingtlie melanic form. Mr. Riches, a variable series of Hyhernia 
leucophcearia from Richmond. Mr. Huckett, suffused forms of Hyhernia 
progemmaria, bred from Epping Forest larvae. Mr. Battley, short series 
of Procris statices, P. geryon and P. glohidarice. Mr. Tremayne, Leucania 
turca, Hyria auroraria and many others, from the New Forest. Mr. 
Prout, series of Gnophos ohscurata taken on the greensand at Sandown 
and chalk at Yentnor; he remarked that although these localities were 
