large. Within the valves ot a dissected specimen there were 

 found in corresponding variety crystals, singly or in laminar 

 groups, examples of which are figured on plate 15 A. 

 Professor S. H. Vines, F.R.S., President of the Linnean 

 Society, having kindly undertaken to examine the shell and 

 some of the detached crystals, writes : — 



' As far as I can make out, these sphaero- crystals are not 

 soluble in boiling water, but dissolve in acetic acid with 

 evolution of bubbles of gas which is no doubt carbon dioxide. 



'* The examination of the piece of carapace seems to show 

 that, for some reason or other, the carbonate of lime has 

 crystallised out from the chitin. The crystals from the 

 inside of the carapace are, I am inclined to think, some of 

 the sphaero-crystals of carbonate of lime which have got free 

 from the carapace altogether. 



" I think that this separation of the lime from the chitin 

 must be due to the action of the preservative in which the 

 animals have been kept, though I am unable to account for 

 it." 



In the Trans. Zool. Soc. London, vol. 16, part 4, April, 

 1902, Dr. G. S. Brady, F.R.S., says in regard to Cyclasterope 

 fascigcra, n. sp., "The antennal setae of this species are often 

 much encumbered, or even glued together by crystalline 

 calcareous concretions similar to those which I have already 

 described and figured as occurring in Philomcdes sculpta." 

 The latter species was described by Dr. Brady in the same 

 Transactions, vol. 14, part 8, December, 1898. Dr. Brady, 

 after discussing the nature of the concretions is disposed " to 

 look upon them as pathological products which have with- 

 drawn the lime otherwise available for shell-formation." 



Mr. W. A. Cunnington, writing from Jena, states that in 

 his study of the common Cladoceran Siinoccphalus he happens 

 " to have noticed that the shed shell (or Ecdysis) is always 

 accompanied by a large number of minute crystals," and 

 asks, " might it be that the calcareous saks in the shell 

 are temporarily dissolved to facilitate ecdysis, and the 

 mineral matter is then thrown down in the presence of the 

 excess of water r " 



That there is some connexion between the presence of the 

 detached crystals and the animal's preparation for changing 

 its coat, seems highly probable. But the Ostracoda must be 

 able to shed the carapace with great ease, and the adhesive 

 character of the crystals under discussion would be so incon- 

 venient to the living crustaceans that it will be satisfactory 

 if the observed conditions can be definitely attributed to the 

 action of the preservative fluid. 



Size: — The largest specimen was 15-5 mm. long by 13 mm. in 

 height, or what may be called the breadth in a lateral view. 

 A1847 ' G 



