Crustacea. 4699 



their shy habits and diminutive size, it can be but rarely ob- 

 served. 



When the period arrives at which the Palaemou serratus is about to 

 throw off its old external covering, it ceases to feed, and seeks about 

 from spot to spot in a restless and fidgety manner, until it has fixed 

 on a locality apparently sufficiently adapted for the purpose required 

 and suited to its fancy ; for this really appears at times to be the case. 

 The third, fourth and fifth pairs of legs are then stretched out wide 

 apart, and the feet hooked so as to hold firmly upon the surrounding 

 substances, in such a way that the body may be poised and capable of 

 moving freely in all directions, as though suspended on gimbals. The 

 prawn then slowly sways itself to and fro, and from side to side, with 

 strong muscular efforts, apparently for the purpose of loosening the 

 whole surface of the body from the carapace; the two pair of prehen- 

 sile or didactylous legs are at the same time kept raised from the 

 ground, stretched forwards, and frequently passed over each other with 

 a rubbing motion, as if to destroy any remaining adhesion ; the eyes 

 also may be observed to be moved within their covering by muscular 

 contraction from side to side ; and when every precaution appears to 

 have been perfectly taken for the withdrawal of its body from its too 

 limited habiliments, a fissure is observed to take place, between the 

 carapace and the abdomen at the upper and back part, and the head, 

 antennae, legs, feet and all their appendages, are slowly and carefully 

 drawn backward and out from the dorsal shield until the eyes are 

 quite clear of the body-shell or carapace, and appear above the upper 

 margin of it ; the prawn thus half released then makes a sudden back- 

 ward spring or jerk, and the whole of the exuvium is left behind, gene- 

 rally adhering by the shell of the six feet to the surface it had selected 

 for its purpose. 



A moment's consideration will develope to the contemplative mind 

 what a truly wondrous process this act of exuviation really is. When 

 we reflect on the small size of this crustacean, and the extreme deli- 

 cacy and intricacy of its various organs, and then find that in this 

 moulting the shell of the most minute and complicated of these struc- 

 tures is thrown off in a complete and unruptured state, even to the 

 gauze-like membrane covering the projecting and pedicled eye, the 

 filamentous antennae, the many-jointed legs, the delicate didactylous 

 hand, the paddled abdomen with its beautiful appendages, the palpi, 

 and all the minute spines and microscopic hairs with which these 

 various members are provided, the human mind can hardly appreciate 



