president’s ADDRESS — SECTION D. 
115 
There is good reason to believe also that our knowledge of these 
animals on the anatomical side will be largely augmented in the near 
future, for within the next year or two we may expect to see Professor 
von Graffs great Monograph of the Land Planarians, and I am glad to 
be able to say that he has had a large number of Australian species for 
investigation. 
Having thus briefly epitomised the history of our knowledge of 
this group in Australasia, we may pass on to the consideration of some 
of the more interesting facts which have been brought to light 
concerning the animals themselves. 
The Land Planarians are an offshoot from the great marine group 
of Turb ell aria, which also has a certain number of representatives in 
fresh water. They are elongated, more or less flattened, and very 
soft-bodied worms, whoso general appearance has earned for them the 
popular title of “leeches” in some parts of Australia, where they 
often occur in great numbers, more than fifty specimens being some- 
times found beneath the same log. In size they vary greatly, from 
the minute Geoplana minor of Queensland, which measures less than 
an inch in length when fully extended in life, to the large Geoplana 
triangulata , var. australis , of New Zealand, of which a specimen in 
the Dunedin Museum measures eight inches in length even after pre- 
servation in alcohol ! They crawl about with an easy, gliding motion, 
in great part due to the abundant cilia with which the integument is 
clothed, and which clearly indicate the aquatic origin of the group. 
The integument at the same time secretes a copious sticky slime, 
which doubtless facilitates the action of the cilia, while at the same 
time it is of service in firmly holding their living prey. As they 
crawl the anterior extremity, which is richly provided with sense 
organs in the form of minute eyes and ciliated pits (probably olfactory 
in function), is uplifted and gently moved about as if prospecting 
the way. In the daytime they are rarely found abroad, but at night 
they may come out and move about freely. 
Considering their love of darkness, it is extremely difficult to 
explain the reason why Land Planarians are so gaily coloured. The 
colours are arranged in longitudinal bands, streaks, or specks, and are 
of every shade: white, red, yellow, green, blue, brown, and black, 
often associated in very beautiful patterns. I have suggested else- 
where* 8 that the very conspicuous colouration of certain species may 
come under the category of warning colours, and thus serve to 
protect the animals from birds when they do happen to venture forth 
in daylight ; but much more evidence is required ou this point. 
Latterly I have observed species in New r Zealand which so closely 
harmonise in colour with their surroundings that one is tempted to 
consider them as instances of protective resemblance. Thus Geoplana 
triangulata , var. australis, occurs abundantly in the beech forest in the 
South Island of New Zealand; and the two shades of colour which 
it exhibits — dark-brown on the dorsal and yellow or orange on the 
ventral surface — almost exactly match the dead beech-leaves which 
strew the ground around its haunts, and which usually show either 
one or the other of these colours. G . gelatinosa , again, from the 
* Trans. Royal Soc. Victoria, vol. 2, part 1, p. 69. 
