8 



PULMONATA. 



Cryptella (canariensis), Webb Sf- Berthelot, Ann. Sci. Nat. 1833, 

 xxviii,, in Gray, Proc. Zool. Soc. 1847, 170. n. 442. 



Guerin, Mag. Zool. t. 36. 



Troschel, Wiegm. Arch. 1836, ii. 210. 



Desk, in Lamk. Hist. vii. 712. 

 Cryptellus, D'Orb. Moll. Cuba, i. 237. 

 Parmacella (ambigua, sp.), Fe'russac, Hist. Moll. 



Sow. Gen. Shells, xiii. t. 103. 



Philippi, Handb. 240. 

 Testacella, sp. (ambiguus), Ferussac, Moll. Terr. 9. 6. t. 8. f. 4. 



1. Cryptella ambigua. B.M. 



Nucleus of the shell very thick, sohd, covered with a green 

 pohshed periostraca, with only half a whorl exposed ; the rest 

 of the shell thick, white, covered with the mantle of the adult 

 animal. 



Testacellus ambiguus, Ferussac, Tab. Syst. 27 ; Hist. Moll. ii. 



95. t. 8. f. 4 ; t. 8 D. f. 9. 

 Parmacella calyculata. Sow. Gen. Shells, xiii. t. 103, 1823. 

 Parmacella ambigua, Philippi, Handb. 240. 

 Cryptella canariensis, Webb ^- Berth. Ann. Sci. Nat. 1833, xxviii. 

 Cryptella ambigua, D'Orb. Hist. Nat. Canar. 50. t. 1. f. 1-12. 



Gray, Fig. Moll. iv. 113. t. 204. f. 1, t. 283. f. 5. 

 Hab. Canary Islands. 



The Cryptella: leave their egg covered with a shell furnished 

 with an operculum. The animal when born is entirely contained 

 in the voang shell, on the edge of which is afterwards developed 

 the second concretion. They are condemned to carry during the 

 rest of their hfe the envelope that served them for a cradle, al- 

 though in enlarging this part of the shell, they gradually till up 

 the cavity which formerly contained the body. 



The operculum is said to be formed a little l)efore the animal 

 leaves its egg ; it is horny, thin, encrusted on the surface, or- 

 bicvdar beneath, conical and swollen above, like that (an epi- 

 phragm) oi Helix naticoides; its colour is dark brown; as the 

 animal increases in size, it gradually leaves its shell ; its tail 

 first appears too large to enter the shell, but we have not been 

 able to fix precisely the time when it throws otf its operculum. 



The animal commences to elongate externally, at the same 

 time that the edge of the shell enlarges into the shape of a disk 

 to cover the most important viscera, the protruding body aug- 

 menting by degrees under the mantle until the animal acquires 

 the adult {orm.— Webb ^ Berthelot, 51. 



Is it a true operculum ? The authors compare it with the epi- 

 phragm of Helix naticoides. 



