MONSTROSITIES OF THE SHELL 



251 



More serious forms of monstrosity are those which occur in 

 individual cases. Mr. S. P. Woodward once observed^ a speci- 

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

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

 the bod}^ whorl. The younger snail had died during its first 

 hibernation, as was shown by 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 entan- 

 gled in a somewhat similar way (Fig. 160 B), possibly as a 



Fig. 158. — Monstrosities of Neptunea an- 

 tiqua L., and Buccinum undatum L., 

 with a greatly produced spire (from 

 specimens in the Brit. Mus.). 



Fig. 159. —Monstrosities of Littorina 

 rudis Mat, The Fleet, Weymouth. 

 (After Sykes.) 



result of embryonic fusion. Double apertures are not uncom- 

 mon 2 in the more produced land-shells, such as Cylindrella and 

 Clausilia (Fig. 160 A). In the Pickering collection was a 

 Helix hortensis which had crawled into a nutshell when young, 

 and, growing too large to escape, had to carry about this de- 

 cidedly extra shell to the end of its days. A monstrosity of 

 the cornucopia form, in which the whorls are uncoiled almost 

 throughout, is of exceedingly rare occurrence (Fig. 161). 



Some decades ago ingenious Frenchmen amused themselves 

 by creating artificial monstrosities. H aspersa was taken from 

 its shell, by carefully breaking it aAvay, and then introduced 

 into another shell of similar size (jET. nemoralis^ vermiculata, or 



1 Ann. 3Iag. Nat. Hist. (2) xvi. p. 298. 



2 See, for instance, Quart. Journ. Conch, i. p. 340 (^Oyl. Baveni) : Jahrb. 

 Deut. Malak. Gesell. 1879, p. 98 (^Clausilia dubia). 



