480 



THE OCEAN WOKLD. 



of Prawn as wlien extracted from the egg. Mr. Yaughan Thomson, 

 by many successive observations, and under the fire of much adverse 

 criticism, satisfactorily established the truth of metamorphic change 

 in many genera, and, in particular, in regard to the common crab 

 (Cancer pagurus) ; having succeeded in hatching the ova of this 

 species, the product of which were fine Zoeas. That there are varia- 

 tions in the channel of this law of change has been admitted, but that 

 generally a metamorphosis exists, analogous to that of insects, in the 

 various genera of Grustacea, with hardly an exception, has been clearly 

 established. 



The recorded observations of the eminent naturalist we have men- 

 tioned, Mr. Thomson, as well as those of Mr. Couch, of Penzance, 

 Mr. Milne Edwards, and particularly those of the last mentioned, the 



Fig. 331. Zoea Taurus. 



learned author of perhaps the best work extant on the Crustacea, are 

 referred to as treating most lucidly on this interesting subject. 



