1892. J 



THE BRITISH NATURALIST. 



75 



by the poor of that district. The original ancestor of these reversed 

 shells was probably produced in a manner analogous to that of the 

 variations in the vegetable kingdom, which gardeners term "sports," 

 these occur more frequently among highly cultivated species than 

 among wild plants, monstrosities are also more commonly observed 

 in domesticated animals than in the wild. In fact, tliose circum- 

 stances which are highly favourable to the individual seem also to 

 favour abnormal growth. This may serve in some degree to explain 

 the occurrence of reversed examples of two species in the same 

 neighbourhood. When one such Helix has been produced, and bred, 

 I should expect to find among the decendants othr^rs of a similar 

 character. If conchologists v/ho are so fortunate as to find reversed 

 and scalariform examples would note such facts as luxuriance of food 

 plants, humidity, sheltered position, &c., some light might be throv^ai 

 on the circumstances favouring tlie production of these forms. Mr. 

 Cockerell also mentions certain examples of H. aspersa, H. nemoralis, 

 and H. hortensis, all collected on the same bank, and having 

 peculiarities in common ; a straw-yellow tinge of the ground-colour 

 with red-brown bandings or markings. No description of the 

 locality is given further than that they were sent from Torquay. In 

 another place, speaking of banding, he says "I am somewhat inclined 

 to suppose that dryness tends to produce forms with the bands much 

 split up and yet distinct. I find this tendency in American examples 

 of H. liovtensis, and it occurs in excess in //. pisana v/hich always 

 frequents hot and dry localities." Mr. Tomlin, in 1888, recorded the 

 occurrence of a single example of H. caperata having translucent 

 bands, in company with H. virgnta of like banding. These 

 observations tend to sho^v that there are certain local circumstances 

 whicli tend to produce variation m certain directions, and, 1 think, a 

 careful record of the conditions under which abnormal forms and rare 

 varieties have been found would throw much light on tlie causes of 

 these variations. With regard to the descendants of Albinos, Mr. 

 J. W. Williams, writing in 1886, says " In cases of albino [Helix 

 grisea, Linn.), Dr. Martinati obser\'ed that tlieir produce were normal." 

 It would be interesting to know the extent of his experiments with 

 these mollusks, as his results are very different to those arrived at by 

 my correspondent. Dr. Haeusler (1 find I misspelt his name in a 

 former paper), with Pupa dolium, and to my own observations with 

 regard to H. hispida. On leaving England, Dr. Haeusler sent me 

 his remaining living examples of P. dolium, and albinos certainly 

 predominated among them, the others being of a lighter colour than 

 the type. — W. A. Cjain. 



