MEMOIR I. 65 



the facts now adduced, further instances will be given in 

 future Memoirs." 



In the first Memoir also, when speaking of the satisfactory 

 explanation which this discovery gives of the annual visits 

 of the Land- Crabs to the sea, in order to deposit their 

 spawn in that element, he appears to have been misunder- 

 stood, for hitherto the rationale of this long and dangerous 

 journey did not appear. Naturalists have thought it 

 strange and inexplicable, that an animal decidedly and 

 wholly terrestrial, should not spawn in its native haunts, 

 and rear its young at home, instead of putting them to 

 the trouble and risk of a tedious and unknown route back 

 again in their very tender age. There could scarcely be a 

 stronger confirmation than this very circumstance of the 

 universality of metamorphosis, for if there were any 

 exceptions, it would certainly be made in favour of the 

 terrestrial species, but no, they are, when first hatched, 

 incapable of living out of water, with members solely 

 adapted to swimming, hence the parent is impelled by 

 its instinct to seek that element for its progeny, which 

 nature has designed for the whole of the tribe to which they 

 belong. Having been many years amongst the West India 

 Islands, with the facts connected with the land-crabs 

 constantly before me, I could never invent any plausible 

 excuse for this curious piece of economy, nor indeed any 

 one else, which should teach us to regard with complai- 

 sance the deviations and eccentricities which we observe 

 in Nature, and which have all, no doubt, some specific 

 object in view, although difficult or impossible for us to 

 discover. 



I avail myself of this opportunity to correct an error in 

 the Explanation of the Plates to the Memoir on Zoea, 

 p. 33, where in Plate II. fig. 8, the Uvo antennae from 

 the same side are figured, a. being the inner, and b. the 

 outer antenna. 



v^ 



