Molluscous Animals of the Genus Gastrochcsna. 401 



In Vol. II. p. 458. are given a figure and description of a 

 presumed new species of snake, discovered near Dumfries, in 

 Scotland, by Mr. T. M. Simmons. Has a second individual 

 of this snake been met with ? and has its presumed distinct- 

 ness as a species been confirmed ? — J. D. 



rbsi rofo>-bol> yahd \ hr; 4- n , 



Art. V. Observations on the Molluscous Animals of the Genus 

 Gastrochce^na, preceded by some Strictures on the reputed Means 

 by which the Burrowing Mollusca effect ingress into Rocks and 

 Stones under Water. By Frederick C. Lukis, Esq. 

 ntidrain bffirfl 



There are few creatures among the Mollusca which pre- 

 sent more interesting details than those of the genera Pholas, 

 Saxicava, m$. Gastrochae'na. The difficulties offered to our 

 researches by their hidden habitation, and the variety of their 

 characters and habits, oppose the exertions of the naturalist, 

 and contribute to the permanence of the marvellous and 

 extraordinary accounts which have been stated concerning 

 them. They are said to usually inhabit limestone rocks, 

 which they perforate by means either of a dissolving power 

 they possess, or by a mechanical boring of the rocks by their 

 own shells. By one or other of these means, or a com- 

 bination of both, they are said to soften or reduce the stone 

 intended to afford them a future place of habitation. By 

 some it is imagined that the animals secrete an acid, or 

 powerful solvent, capable of affecting the stone in which they 

 are so frequently found; and that they, at the same time, can 

 yet prevent that solvent from injuring their own calcareous 

 covering. By others it has been advanced that they have 

 the power to soften the spot on which they fix, and then 

 introduce themselves into the rock by the attrition of their 

 own shells. Although many instances offer themselves to 

 foster and support, in some degree, these opinions, still 

 considerable difficulties are presented to our observations in 

 the process of examining this curious tribe of Mollusca. 



It cannot be denied that, whatever powers they are en- 

 dowed with in common with other shelled Mollusca, they have 

 capabilities above those of many kinds, by which they are 

 enabled to accommodate themselves to situations very different 

 from those appropriated by others. If, however, they are 

 discovered in a locality where they may be thought to bd 

 necessitated to put forth a solvent, or eroding power, to 

 procure a permanent concealment, they are, nevertheless, 

 found equally in situations where no such exertion is required. 

 Vol. VI. — No. 35. dd 



