458 A MANUAL OF AMERICAN LAND SHELLS. 



whorls which are no longer of use. * This commences at a very early 

 period, the original apex being thrown off when the shell has acquired 

 6 or 6 whorls. They differ in this particular from most of land-shells, 

 and especially from the Helices, which always, so far as I know, retain 

 their original attachment to the apex of the shell. It has been thought 

 that the breaking of the spire, after being left by the animal and be- 

 coming dry and brittle, is accidental ; but I conceive that the effect is 

 much too constant to be accounted for in that way. I have never been 

 able to find a mature specimen with the apex. And in all the various 

 countries which it inhabits, including the whole southern part of 

 Europe, the northern part of Africa, the islands of the Mediterranean, 

 the Canaries, Madeira, &c., the same peculiarity attends it. If it were 

 only an accident, some few in this wide extent might escape. I doubt 

 not, therefore, that it is effected by the action of the animal itself. It 

 may be that the calcareous matter of the shell is absorbed at the point 

 of division previous to the formation of the new septum. 



Mr. Say made out his description from an immature specimen. 



The epiphragm is white, pearly, and opaque ; it fills up the aperture, 

 and when i^ushed out by the animal generally falls entire. It may be 

 f«een in numbers about their winter quarters. Its outline is repre- 

 sented in Terr. Moll.', Ill, Plate 1. 



Jaw and lingual membrane : see pp. 423, 424. 



Lingual membrane (Terr. Moll., Plate IV, Fig. Q, ft, and also my 



Fig. 500, Fig. 500, is one of the first marginals, c extreme mar- 



^ r\ r\<rf^ ginal) — a Charleston specimen : There are 38-1-38 teeth, 



'^ ^M AM^ with 11 perfect laterals (see p. 424). 



The genitalia are figured by Leidy (Terr. Moll., I, 



Lingual dentitiou of 



s. decoiiata. pj^te XV, Figs. 5, 6). The genital bladder (6) is small, 

 globular, with a short, narrow duct entering the vagina near its upper 

 end; the penis sac (3) is short, stout, cylindrical, with a median con- 

 striction ; it receives the vas deferens and retractor muscle at its apex. 



ARIOJV, FiiRussAc. 



Animal limaciform (see Terr. Moll., Ill, Plate LXIV, Fig. 1). Pos- 

 terior termination of body obtuse. Integuments crowded with elongated 

 tuberosities on the back, and on the sides with elongated, tubercular 

 plates having furrows between. Mantle anterior, oval, small, covered 



* Moquin-Tandon says (on the authority of Gassies) that the animal breaks off the 

 upper whorls by jerking round its shell against some hard object. 



