332 Intelligejice and Miscellaneous Articles. 



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 fluviatUis, 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 cornese, as well as the antennse, 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, llie jaws, foot-jaws, and ambulatory feet retain their original 

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

 thrown off 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 

 delicate organs. No fissure was perceptible in any of the articula- 

 tions of the small claws, but in the chela each segment was split in 

 the neighbourhood of the joints and the articulated ligaments rup- 

 tured. The lining membrane of the stomach was found in the tho- 

 rax, having the stomachal teeth connected with it ; from its position 

 it would seem that the animal had dropped it into the place where it 

 lay before the exti'ication of its limbs was quite accomplished. The 

 internal tendons were all attached to the moveable joint of each pair 

 of foi'ccps, both in the chela and in the two anterior pairs of smaller 

 ambulatory legs. 



" On examining the animal, which had extricated itself from the 

 exuvium described above, the shell was found soft and flexible, but 

 contained a sufiiciency of calcareous matter to give it some firmness, 

 especially in the claws. The tendons of the forceps were still per- 

 fectly membranous, presenting a very decided contrast when com- 

 pared with the old ones afiixed to the discarded shell. The stump 

 of the lost chela had not as yet begun to s])rout, and the extremity 

 was covered by a soft black membrane. I'he jaws were quite hard 

 and calcified, as likewise were the teeth contained in the stomach." 



