MONSTROSITIES OF THE SHELL 



251 



More serious forms of monstrosity are those which occur in 

 individual cases. Mr. S. P. Woodward once observed ^ a specimen 

 of an adult Helix aspersa with a second, half-grown individual 

 fixed to its spire, and partly embedded in the suture of the body 

 whorl. The younger snail had died during its first hibernation, 

 as was shown l)y the epiphragm remaining in the aperture, and 

 its neighbour, not being able to get free of the incubus, partially 

 enveloped it in the course of its growth. In the British Museum 

 two Littorina littorea have become entangled in a some- 

 what similar way (Fig. 160 B), possibly as a result of embryonic 



A + +B 



Fig. 159. — Monstrosities of Littorina 

 ■nulis Blat, The Fleet, Weymoiitli. 

 (After Sykes.) 



Fig. 15S. — Monstrosities of Xeptunea an- 

 tiqua L., and Buccinum undatum L. , 

 witli a gi-eatly produced spire (from 

 .specimens in the Brit. Mus.) 



fusion. Double apertures are not uncommon ^ in the more 

 produced land-shells, such as Cylindrella and Clcmsilia (Fig. 

 160 A). In tlie Pickering collection was a Helix hortcmsis 

 whicli had crawled into a nutshell when young, and, growing 

 too large to escape, had to carry about this decidedly extra shell 

 to tlie end of its days. A monstrosity of the cornucopia form, 

 in which the whorls are uncoiled almost throughout, is of exceed- 

 ingly rare occurrence (Fig. 161). 



Some decades ago ingenious Frenchmen amused tliemselves 

 by creating artificial monstrosities. H aspersa was taken from 

 its shell, by carefully breaking it away, and then introduced into 

 another shell of similar size {H nemoralis, Termiculata, or 



^ Ann. Mag. Nat. Hist. (2) xvi. p. 298. 



- See, for instance, Quart. Journ. Conch, i. p. 340 {Cijl. llaccui) : Jahrh. Dcut. 

 Malak. Gesell. 1879, p. 98 (Clausilia duUa). 



