28 RIO DE JANEIRO chap. 



spend some weeks in so magnificent a country. In England 

 any person fond of natural history enjoys in his walks a great 

 advantage, by always having something to attract his attention ; 

 but in these fertile climates, teeming with life, the attractions 

 are so numerous, that he is scarcely able to walk at all. 



The few observations which I was enabled to make were 

 almost exclusively confined to the invertebrate animals. The 

 existence of a division of the genus Planaria, which inhabits the 

 dry land, interested me much. These animals are of so simple 

 a structure, that Cuvier has arranged them with the intestinal 

 worms, though never found within the bodies of other animals. 

 Numerous species inhabit both salt and fresh water ; but those 

 to which I allude were found, even in the drier parts of the forest, 

 beneath logs of rotten wood, on which I believe they feed. In 

 general form they resemble little slugs, but are very much nar- 

 rower in proportion, and several of the species are beautifully 

 coloured with longitudinal stripes. Their structure is very 

 simple : near the middle of the under or crawling surface there 

 are two small transverse slits, from the anterior one of which a 

 funnel-shaped and highly irritable mouth can be protruded. 

 For some time after the rest of the animal was completely dead 

 from the effects of salt water or any other cause, this organ still 

 retained its vitality. 



I found no less than twelve different species of terrestrial 

 Planariae in different parts of the southern hemisphere.-^ Some 

 specimens which I obtained at Van Diemen's Land, I kept alive 

 for nearly two months, feeding them on rotten wood. Having 

 cut one of them transversely into two nearly equal parts, in the 

 course of a fortnight both had the shape of perfect animals. I 

 had, however, so divided the body, that one of the halves con- 

 tained both the inferior orifices, and the other, in consequence, 

 none. In the course of twenty-five days from the operation, the 

 more perfect half could not have been distinguished from any 

 other specimen. The other had increased much in size ; and 

 towards its posterior end, a clear space was formed in the par- 

 enchymatous mass, in which a rudimentary cup-shaped mouth 

 could clearly be distinguished ; on the under surface, however, 

 no corresponding slit was yet open. If the increased heat of the 



1 I have described and named these species in the Annals of Nat. Hist. vol. xiv, 

 p. 241. 



