INTRODUCTION. 



lix 



tovy, communicated two papers to the Annals of Natural 

 History, on the Metamorphosis of Crustacea. To one of 

 these, on Carcinus Manas, I have already alluded ; the 

 other * contains a brief account of the transformation and 

 development of the ditch prawn, Palemon varians, in 

 four stages, accompanied by excellent figures ; and a still 

 more slight one of the common shrimp, Crangon vul- 

 garis, in its first stage only. I give that author's figure 

 of the first stage of the prawn (fig. k), in which the 



locomotive organs are pro- 

 bably the homologues of the 

 foot-jaws, and the rudiments 

 of some of the true feet ap- 

 pear under the cephalo-tho- 

 rax. The eyes are wholly 

 sessile ; there is not the 

 slightest appearance of ab- 

 dominal members ; and the 

 simple spatulate form of 

 the tail is remarkably dif- 

 ferent from the highly de- 

 veloped and complicated 

 structure of that organ in 

 the adult. 



The two following figures 

 exhibit two successive states 

 of the young animal, gra- 

 dually approaching more 

 and more to the adult con- 

 dition. In Fig /, is seen one of the serratures of the 



* Ann. Nat. Hist. vol. ii. p. 178, pi. vi. and vii. 



