133 



antice vix descendente ; umbilico mediocri, pervio ; aperturd roturi' 

 dato-lumri ; peristomate ea:panso, intus remote albo-labiato, mur- 

 ginibus coimiventibus, cohmellari subdilatato, patente. 



Diam. 17, alt. 9^ mill. 



From the banks of the river Tortoom (As. Russ.) ; found ia damp 

 meadows, 



" On the Growth and Re-calcification of the Shell in Cypraa, a 

 genus of Pectinibranchiate Mollusca" : — 



The Cypraa is a mollusk of very peculiar character : first, on ac- 

 count of the difFerent phases presented by its shell at diflferent periods 

 of growth ; aud, secondly, on account of the curious property which 

 the animal possesses of dissolving and renewing its shell. The 

 original growth of the Cowry is, undoubtedly, a process of time ; but 

 the re-calcification of a shell at maturer age appears to be the -vvork 

 of a few days only. 



The first stage of advancement produces a simple convolution of 

 shell around a columella axis in the form of a long drawn-out Bulla, 

 the columella being smooth, the outer lip thin, and the colour usually 

 difFused in bands of \vaves. In the second epoch of grovvth the shell 

 solidifies, the lip and columella begin to thicken, and present gradual 

 indications of teeth, the teeth become more and mere perfectly de- 

 veloped, and the dorsal surface is overlaid with a strong coat of livid 

 colouring matter also difFused in obscure bands or waves. The cal- 

 cifying energies of the mantle; which, extending in two uneąual lobes, 

 one from either side of the shell's aperture, have been chiefly exer- 

 cised during the second epoch of growth upon the dorsal surface, are 

 now more particularly directed to the base and sides. The teeth are 

 strengthened, the sides become thickened with a rich coating of 

 enamel, and the gro\vth of the shell is completed by a light fabric of 

 colouring matter deposed in lines, blotches, waves, or reticulations, 

 of various hues and jjatterns. 



The re-calcification of a shell at maturer age has been a subject of 

 some difFerence of opinion amongst naturalists. Bruguiėre first in- 

 troduced the fact, and Lamarck says, " I possess obsei-vations \vhich 

 tend to p rovė that the Cowry, arrived at the power of forming a 

 complete shell, has still the faculty of enlarging its habitation, and 

 is then obliged to quit the shell in order to form a new one. It re- 

 sults from this that the šame individual has the power of forming a 

 successive number of shells during both the second and third stagea 

 of growth, and which accounts for our often meeting \vith so many 

 diflTereut sizes of the šame species" ! 



M. Deshayes, after furnishing us \vith an escellent account of the 

 zoological characters of Cypreea, derived mainly from the observations 

 of MM. Quoy and Gaimard, argues against the possibiHty of any 

 remodelling of the shell taking place, and regards the statement 

 of Lamarck as a theory opposed to the common laws of organiza- 

 tion. To the supposition of Bruguiėre that the Cowries cast their 

 shells after the manner of Crabs, M. Deshayes very properly replies 

 that there can be no analogy between them. The new shell of the 



