142 Miscellaneous, 



it still encased the living member. The only way of explaining the 

 circumstance, is to suppose that the individual pieces of the skeleton, 

 as well as the soft articulations connecting them, split in a longitu- 

 dinal direction, and that, after the abstraction of the limb, the fis- 

 sured parts close again with so much accuracy that even the traces 

 of the division are imperceptible. But this is not the only part of 

 the process which is calculated to excite our astonishment : the in- 

 ternal calcareous septa from which the muscles derive their origins, 

 and the tendons whereby they are inserted into the moveable por- 

 tions of the outer shell, are likewise stated to be found attached to 

 the exuvise ; even the singular dental apparatus situated in the sto- 

 mach, of which we shall speak hereafter, is cast off and re-formed I 

 And yet, how is all this accomplished ? how do such parts become 

 detached ? how are they renewed ? We apprehend that more 

 puzzling questions than these can scarcely be propounded to the 

 physiologist, nor could more interesting subjects of inquiry be 

 pointed out to those whose opportunities enable them to prosecute 

 researches connected with their elucidation." 



In a note annexed to this paragraph he describes the appearances 

 of an Astacus fluviatilis, which he had obtained soon after casting its 

 shell, and of its newly cast-ofF covering. '* All the pieces of the ex- 

 uvium are connected together by the old articulations, and accu- 

 rately represent the external form of the complete animal ; the cara- 

 pace, or dorsal shield of the cephalo- thorax alone being detached, 

 having been thrown off in one piece. The pedicles of the eyes and 

 external corneae, as well as the antennae, remain in situ, the corre- 

 sponding parts having been drawn out from them as the finger from 

 a glove, and no fissure of the shell or rupture of the ligaments con- 

 necting the joints is anywhere visible in these portions of the ske- 

 leton. The ordinary tubercles, and the membrane stretched over 

 the orifice of the ear, occupy the same position as in the living cray- 

 fish. The jaws, foot-jaws, and ambulatory feet retain their original 

 connections, with the exception of the right chela, which had been 

 thrown of before the moult began ; and the segments of the abdo- 

 men, false feet, and tail-fin exactly resembled those of the perfect 

 creature ; — even the internal processes derived from the thoracic 

 segments (apodemata) rather seemed to have had the flesh most care- 

 fully picked out from among them than to have been cast away from 

 a living animal : but perhaps the most curious circumstance obser- 

 vable was, that attached to the base of each leg was the skin which 

 had formerly covered the branchial tufts, and which, when floated in 

 water, spread out into accurate representations of those exquisitely 



