4146 Notices of New Books. 



These, if even the statements were fully borne out, have since been 

 proved to be merely exceptional cases ; and not only is Mr. Rathke's 

 assumed general support of Mr. Westwood's objections completely 

 removed, but that distinguished physiologist himself volunteers his 

 strong testimony in favour of the opposite views in a subsequent pa- 

 per, in which he says that he hastens the publication of these new 

 researches respecting the development of several other forms of Crus- 

 tacea, one of which is the lobster, 6 in order, as soon as possible, to 

 record a testimony to the correctness of Thompson's discovery, that 

 even the Decapods, after they have already quitted the egg, undergo 

 a very considerable metamorphosis ; ' and, in conclusion, he adds, 

 1 from the notices which I have here briefly communicated respecting 

 the development of some Decapods, it results that several of these 

 animals, as first discovered and described by Thompson, undergo a 



very considerable and highly remarkable metamorphosis 



I, therefore, confess that I have done Thompson injustice in not put- 

 ting faith in that discovery.' And he then states his intention, ' next 

 spring, partially to subject his researches on the cray-fish to revision.' 

 There is one apparent anomaly, however, on which Mr. Westwood 

 dwells with some plausible show of reason, and on which it may be 

 well to offer a few remarks. 



" Amongst the specimens of Crustacea, preserved in spirits, which 

 formed part of the collection of the late Rev. Lansdown Guilding, 

 and which came into my possession after his death, was one of the 

 abdomen of a female land crab (Gecarcinus), to which were attached 

 numerous young, in their perfect form, and very similar, excepting in 

 size, to the parent. Here, then, was a case in which, it may at once 

 be granted, no external and independent metamorphosis, at least, had 

 taken place ; and on this, with the other instances above alluded to, 

 Mr. Westwood founds his principal argument against the doctrine 

 enunciated by Mr. Thompson. But may not this probably be an 

 analogous phenomenon to that of the land salamanders amongst the 

 Amphibia ? And, as in that instance, where the animal has no 

 opportunity of depositing her eggs in the water, where, in the more 

 typical forms, the young undergo the transformations essential to the 

 whole group, the changes take place in the oviduct ; so may not the 

 young of the land crab, whose habits require them to be speedily in a 

 condition to leave the coast where they are hatched, formally undergo 

 the metamorphosis within the egg ? This being granted, it would be 

 as reasonable to deny the phenomenon of transformation in the Am- 

 phibia generally, because the young of the salamander are brought 



