1832.] PLANARLE. 27 
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 re- 
tained its vitality. 
I found no less than twelve different species of terrestrial Pla- 
nariz 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 to- 
wards its posterior end, a clear space was formed in the pa- 
renchymatous 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 
weather, as we approached the equator, had not destroyed all 
the individuals, there can be no doubt that this last step woula 
have completed its structure. ‘Although so well-known an ex- 
periment, it was interesting to watch the gradual production of 
every essential organ, out of the simple extremity of another 
animal. It is extremely difficult to preserve these Planariz ; as 
soon as the cessation of life allows the ordinary laws of change 
to act, their entire bodies become soft and fluid, with a rapidity 
which I have never seen equalled. 
I first visited the forest in which these Planarie were found, 
in company with an old Portuguese priest who took me out to 
hunt with him. The sport consisted in turning into the cover 
* I have described and named these species in the ‘ Annals of Nat, Hist.,’ 
vol. xiv. p. 241. 
