TAYLOR : LIFE HISTORY OF HELIX ASPERSA. 9I 



Doctor Turton has confounded the synonyms of the aspersa 

 with those of the hortensis, not considering the former as an 

 Enghsh shell, and therefore has quoted this shell of Lister, 

 Pennant and Da Costa for the hortensis." Mont. p. 410. 



Helix secu?ida Costa, ff. Fhiminensis Lang, and H. spumosa 

 Lowe, are given on the authority of Dr. Pfeiffer. 



Rimmer queries whether aspersa was not a slip of Mliller's 



pen for aspera. 



Classification. 



This species is now generally placed in the subgenus 



Pomatia of Leach, a group of which the characteristics are : — 



Shell imperforate or subimperforate, globose, striate, 

 calcareous-horny, generally banded, whorls 4 — 6, convex, the 

 last large, ventricose, descending, aperture lunate-orbicular, 

 peristome patulous or straight, labiate within, the columella 

 margin reflected, generally callous. 



Dr. Westerlund places it nnder Helicogena^ following 



Ferussac, but the characters of the group are precisely those of 



Pomatia Leach. Dr. Gray places it in Acavus, of which Helix 



hminosto7?ia L., a native of Ceylon, is the type. Moquin-Tandon 



places it in Cryptomphalus Agassiz, regarded by Prof, von 



Martens as a section of Pomatia., differing in the less solid shell, 



and flat and more membranous epiphragm. 



Development. 



The eggs are laid from May to October in 5 to 8 days after 

 pairing, and hatch in from 15 — 30 days. They are from 

 4 — A^\ mill, in diameter, of somewat oval form, and are brilliant 

 white or greenish-white in colour, with an opaque, shining, 

 membranous and very elastic envelope, so that they rebound 

 on falling on a solid object. On exposure they dry in, to an 

 an irregular shape, and if dropped into water in this state they 

 fall to the bottom. Their weight is about 35 millegrammes. 

 They vary in number according to Moquin-Tandon from 50 — 80, 

 and to Bouchard-Chantereuxfrom 100 — 1 10, but when individuals 

 couple young the number of eggs laid by them is less. M. 

 Gassies says they are placed in holes containing about 50 eggs 



