52 BRITISH MOLLUSKS. 



they are not so defined over the periphery as in Z. radiatulus. 

 Mr. Benson is erroneously quoted by Gray, Forbes and Hanley, 

 and Moquin-Tandon, as having given the generic name of Tany- 

 chlamys to this species. It was for Dr. Gray's genus Nomina that 

 Mr. Benson proposed that name, referring at the same time to an 

 Indian species, which he merely described in general terms, as re- 

 sembling Z. nitidus, but of larger size. Z. nitidus is well known to 

 gardeners, from its habit of infesting pine beds and orchid houses. 



7. Zonites excavatus. Excavated Zonites. 

 Shell ; largely excavately umbilicated, convexly depressed, fulvous 

 horny, spire rather exserted, suture moderately 

 impressed, whorls four to four and a half, slopingly 

 convex, enlarging slowly, aperture small, striated 

 throughout ; aperture obHquely lunar-rounded. 

 Helix vitrina, Ferussac (1821), Tall. Syst. p. 41 (without cha- 

 racters) . 

 Helix excavata, Bean (1830), Alder, Trans. Nat. Hist. Soc. 



Northimib. toI. L p. 38. 

 Helix viridula, Menke (1830), Syn. Moll. p. 20. 

 Helix nitida var., Jeffreys (1830), Trans. Linn. Soe. vol. xvi. 



pp. 339, 511. 

 Helix petronella, Charpentier (1837), Moll, de la Suisse. 

 Zonites excavatus, Gray (1840), Turt. Man. p. 175. pi. xiii. f. ]38- 

 Hab. Northern and Central Europe. Throughout Bi'itain, but local (under 

 decayed timber). 

 To a casual observer, this shell has very much the appearance of 

 Z. nitidus, but it will be seen on comparison to be composed of 

 narrower whorls, increasing more slowly in width, and coiling round 

 a broader axis. The umbilicus thus acquires a perspectively exca- 

 vated Itotella-like appearance. The whorls drop a little more in 

 the coiling, which renders the spire more exserted, while the sutural 

 line is less strongly impressed. Dr. Gray states that the animal is 

 lead-coloured but lighter, and frequents a different situation, being 

 found under decayed wood and timber that has lain some time on 

 the. ground. 



Mr. Jeffreys has lately recorded his opinion that Helix viridula, 

 Menke, and Zonites excavatus, Bean, described in the same year, are 

 one and the same species, having identified British specimens of the 

 latter with Continental specimens of the former collected by him- 



