ALGA GROWING ON THE EUROPEAN TORTOISE. 258 - 
shape and are all exactly alike; they swim about for a consider- 
able time and then germinate. Sexual reproduction has as yet 
not been observed. 
As regards the mode of life of the alga, from the fact that sec- 
tions separated from the tortoise can be kept alive for a consi- 
derable time, during which the cells can grow and produce 
zoospores, it would seem that the alga derives no nourishment 
‘from the tortoise; yet the alga derives very great benefits from 
its mode of life, for the tortoise, though spending a great part 
of its time in water, is able to wander about from pool to pool, 
and thus conveying the alga with it, effects its distribution geo- 
graphically. Again, during dry seasons, when a pool of water in 
which a tortoise infected with the alga becomes dried up, the 
tortoise is able to migrate to another, and generally does so at 
night, and hides in the shade during the day; in case it cannot 
find water in this way, the alga is kept alive by not being ex- 
posed to the heat of the sun. We must therefore at present 
regard the alga as an epiphyte, since at present the observations 
tend to show that no nourishment is derived from the tortoise. 
At present, since the sexual reproduction of Dermatophyton is 
unknown, its proper place in the classification of the Alg® cannot 
be assigned; yet it evidently belongs to the Chlorophycea, and 
most likely to the Ulvacee, in the family Confervoides. 
The alga described in this paper was first given to me by 
Professor Moseley, who had discovered it upon some tortoises 
and who desired me to work out its life-history. I was unable 
anywhere to find a description of it, and referred it to Professor 
Boret and to my friend Mr. George Murray, of the British 
Museum, with a similar result. I delayed to publish a descrip- 
tion until I had found some mode of reproduction ; and with this 
object in view I obtained a grant from the Worts Travelling Fund, 
and proceeded to Portugal in the summer of 1886. As soon 88 
possible on my return, I read a paper before the Cambridge 
Philosophical Society, where I gave to it the name of Epiclem- 
mydia lusitanica *. It was not until December 1886 that I found 
that Dr. Peter, of Munich, had published a mere description and 
had named the alga Dermatophyton radicanst on September 22nd 
of the same year. 
* Proceedings of Camb. Phil. Soc. vol. vi. pt. i. Nov. 8, 1886. 
t Bot. Centralbl. Band xxviii. 1886, p. 125; SB. Versamml. deutsch. Naturf. 
u. Aerzte, Sept. 22, 1886. 
