THE JOURNAL 



OF THE 



(ijiulutt Ipicrascajjital Club, 



Ox THE Microscopic Structure of the Shell of Crustacea. 



By J. Slade. 



(Read May 22nd, 1868.; 



The following notes on the Microscopic Structure of tlie Shell of 

 the Crustacea are partly the result of an examination of a few slides 

 prepared by myself at different times, and from different species of 

 the grouj). 



It is a subject which seems to me to be but little worked upon 

 by microscopists in general, and it is mainly the desire to make it 

 better known, rather than to add anything to that which is already 

 recorded, and also the greater desire that it may lead to discussion, 

 which always gives so much life and energy to our meetings, that I 

 have complied with the request to introduce it to you this evening. 

 About two months ago I brought the same subject before the mem- 

 bers of the N. L. N. Club, and several gentlemen now present will, 

 doubtless, remember it resulted in a warm discussion — the very best 

 effect which a paper of this kind can produce ; and although con- 

 flicting theories could not be reconciled, yet I am sure we were all 

 benefited by the trial of our microscopic and reasoning powers. 



The shell of the common crab may be taken as the type of struc- 

 ture of the shell of all Crustacea, and is much more complex than 

 the shell of any Echinoderm, Mollusc, Brachiopod, or even than tooth 

 or bone. It consists of four layers, with tubules like those of den- 

 tine, traversing them at right angles, or nearly so. 



Dr. Carpenter, in the Report of the British Association for 1848, 

 noticed this tubulated structure, and since then it has been described 



H 



