244 NATURAL HISTORY OF 



agreeable sub-acid flavour, which renders them very grateful 

 to the palate in the warm regions where they ripen. The great 

 drawback of this day was furnished by the mosquitoes and "bar- 

 rachutas," which were very numerous, and bit most savagely. 

 The latter insect, a minute black fly, settles gravely on any 

 exposed part of its victim, inflicting a minute puncture, to 

 which his attention is first attracted by a minute drop of effused 

 blood immediately beneath the cuticle, and which is shortly 

 afterwards followed by a considerable amount of swelling and 

 violent irritation, often lasting for two or three days. These 

 insects, I may remark, ai e not common in the immediate neigh- 

 bourhood of Eio, w^here mosquitoes abound, and their bite is far 

 more virulent in its nature than that of these well-known pests. 

 The following day, while scrambling along the rocks at 

 the side of one of the cascades, I captured a female specimen 

 of a fresh-water crab, of a dull purplish colour, the Tricho- 

 dactylus fluviatilis, very common in Brazil, and was surprised 

 to find between fifty and sixty fully- developed young 

 individuals beneath the pleon or tail-flap, in the position 

 ordinarily occupied by the ova. These little creatures were 

 very active, and several made their escape when their parent 

 was taken. I was much interested by this circumstance, 

 which apparently proves that the young of this species 

 do not pass through any transformation, like the majority 

 of crabs ; or, if they do so, that the different phases are 

 assumed when they are still associated with the mother. 

 Professor Westwood, so long ago as 1835, in a very interest- 

 ing memoir in the Philosophical Transactions, '' On the 

 supposed Existence of Metamorphosis in the Crustacea," 

 pointed out that in certain land-crabs no metamorphosis 

 takes place in the young ; but I am not aware that the fact 

 has been previously recorded as regards the above species. 



