™s 
484 APPENDIX—HELIX NEMORALIS. 
These various surmises as to the location of the evolutionary region are, 
however, all open to the objection that they are based upon the erroneous 
assumption that the area of development or original home of a primitive 
species is always within the area where it exists at the present day, quite 
disregarding the acknowledged facts that new species arise because the 
differences ‘they acquire confer some advantage over the older forms from 
which they have emanated, and that these improved descendants eventu- 
ally displace the ancestral forms. 
A survey of the facts given by Dr. Germain shows them to be in perfect 
harmony with the principles of distribution propounded in the present 
work, which are based on the comparative anatomy and the probable 
phylogenetic history of the organisms. 
Helix nemoralis Linné (see p. 274). 
Physiology and Food.—Mr. R. Welch has remarked on the compara- 
tively small amount of food consumed by this species in confinement, a 
circumstance which may be regarded as confirmatory of the greater bio- 
chemical efficiency of its digestive system, and as another evidence of its 
superiority in the scale of life. 
Geological Distribution.—Putocenr.—In Suffolk, in the Forest Bed 
at West Runton, Mr. Clement Reid has discovered the Helia hwsendoncki 
of Nylander, which he regards as a synonym of the present species. 
In Italy, H. nemoralis is cited by Dr. 'hielens from the lacustrine lime- 
stone of Pliocene age at Monte 'Tignosa, near Leghorn. 
Hotocene.—In Dorset, Mr. Clement Reid has recorded some large 
depressly-globular yellow bandless shells with dark lips from an early 
Neolithic kitchen-midden at Blashenwell. 
In Buckinghamshire, it has been found by Mr. J. E. Cooper in the 
Alluvial brick-earth, ete., at Boveney. 
In North Lincoln, at Greetwell, by Mr. J. F. Musham. 
In Mid-west Yorkshire, Mr. J. Wilfrid Jackson has found it common in 
a Neolithic hill-wash at Clapdale, near Clapham. 
In South-east Yorkshire, according to the Rey. E. P. Blackburn, it has 
been found by Mr. J. Rt. Mortimer in “barrows” of the Bronze age at 
Garbutt’s Garton Slack; in Swinham Plantation, Aldro; at Birdsall Brow ; 
at Wold Newton; at Lingwalk wood ; in Esks road ‘“‘barrow,” Helperthorpe ; 
and in Willie Howe’s plantation. 
Parasites.—The bee Osmia bicolor is said to utilize the empty shell of 
this species for its nest; while another insect Sapyga punctata inhabits the 
same shells and passes through two stages of its existence within the cells 
of the Osmia. 
Variation.—M. Perroud has remarked that monochromic individuals 
are generally most numerous on the banks of rivers, especially in places 
liable to submersion in winter, and other continental observers have 
recorded that the yellow and fasciated varieties are very often found on 
Inula spinosa, 
