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 vitalitv. 
j 
I found no less than twelve different species of terrestrial 
Planarise in different parts of the southern hemisphere. 1 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. 
