[Suppleiueut to the Journal of Malacology, Volume VI., No. /.] 



SOME SCIAGRAPHS OF SHELLS. 



The sciagraphs given on the accompanying plate are 

 of shells in the writer's possession and were kindly made by 

 Messrs. \\'. Watson & Sons of High Holborn, London, expressly 

 for the Journal of Malacology. 



Explanation of Plate IIL 



Figures i to 7 are a series of shells of a cowry Cypraea arabica, 

 from the South Pacific Isles, shewing the changes which take place during 

 growth. 



Figures i and 2. Young specimens, in which the shell is a simple spiral 

 one with a thin unreflected lip. N.B. — The spires are 

 somewhat worn at the tip. 



Figure 3. In this shell the lip has expanded, the edge has curled inwards, 

 and a row of "teeth" is beginning to make its 

 appearance there. 



Figure 4. Here, another row of " teeth " is to be seen on the body of the 

 shell approximately parallel to that on the edge of the lip. 



Figure 5. This shell is thicker owing to the deposition of layers of 

 " nacre " upon its outside by the mantle-flaps which are 

 protruded by the animal and which cover the shell and 

 meet in the middle line on its dorsal surface. The " teeth " 

 are now more evident. 



Figure 6. The thickening process is being carried on, the shell being 

 considerably heavier and more massive. 



Figure 7. The adult shell, in which almost the maximum of thickening 

 has been reached, and the broadening of the shell achieved : 

 the longitudinal expansion of the lip, too, has now hidden 

 the spire of the younger shell. 



Figures 8 to ii are sciagraphs of three land shells which show the 

 columella and the interior of the shell as well as other points noted below. 



Figure 8. A shell of Bitlimits decollatus, from Malta, which looses its top 

 whorls as it grows ; the partition which divided the un- 

 inhabited portion of the shell from the rest is shewn. 



Figure 9. A young shell of the same, still retaining its apex and from its 

 position on the plate shewing how much, shell has been 

 discarded by Figure 8. 



Figure 10. Chutsilia swinboei, from Formosa, showing the clausium or 

 clausilium which guards the entrance of the shell. 



Figure ii. Cochlostyla pltilippinensis, from the Piiilippine Islands. 



Wilfred INIark Webb. 



