AND LIFE-HISTORY OF A TROPICAL EPIPHYLLOUS LICHEN. 111 
for a distinct organ. It would be important to determine whether any process prior to 
the upgrowth of the “ fertile hair" can be regarded as sexual: my observations certainly 
allow no such view. 
Another point, noticed by Cunningham, renders it almost certain that we both refer 
to the same cell in the terms ** oogonium " and “ zoospore-containing cell of the thallus "' 
respectively : he notes (p. 309) that ** the zoospores, when first emitted, are of an oval or 
pear-shaped form." ‘ Eventually they cease to move, and become spherical;" cf. my 
statements, made quite independently and before I had seen the paper referred to, on 
p. 94 of the present memoir. Не is of opinion, however, that these zoospores reproduce 
the plant directly; my observations fail to confirm this. 
It must be admitted that much remains to be done in connexion with the reproduction 
| of this Alga; and probably no more interesting subject presents itself to the investigators 
in tropical and subtropical countries than this. 
It will be obvious that, if my criticism is of value, serious objection must be made to 
the definitions on p. 312 of Cunningham’s paper until more definite knowledge is obtained 
respecting the alleged parasitism and sexual propagation of this Cryptogam and its allies. 
The epiphyllous Lichen referred to in the above paper is clearly not the one here 
described—a fact which may possibly be also quoted against the assumption that the Algee 
are identical, though I cannot admit its validity. 
Something more in detail may now be said as to the systematie position of the Alga 
and resulting Lichen above described; and since Cunningham's new genus “ Mycoidea” 
cannot be accepted on its present basis, the following remarks will also apply generally 
to the organism he described in Calcutta. 
Reference has already been made to the resemblances in external appearance and mode 
of growth of this Alga to what Pringsheim * has described for Coleochete. The most 
striking divergences from that type offered by the new Alga are connected with the 
habitat, the ** fertile hairs," the rhizoids, and the peculiar orange-red contents of the cells. 
These differences are important ; and careful comparison with Coleochete suggests that, 
after all, there is very little in common between the two beyond the mode of growth of 
the disk-like thallus and the production of zoospores from certain cells t. 
Can we suggest any other possible ally? I think we can. The genus Chroolepus pre- 
sents features which agree with what oecurs here in several important points. In the 
orange-red oily cell-contents, in habitat, and in the production of similar zoospores in 
ovoid cells developed terminally and laterally from the cell series, we have remarkable 
points of agreement between the two forms i. The mode of growth of the disk in our 
Alga is in no way subversive of the value of these analogies, if we reflect that here, as in 
* Jahrbuch für wissenchaftliche Botanik, ii. 1. 
t I may here place on record the discovery of some very minute shield-like bodies attached to the threads of Con- 
fervee and Chotomorpha found on the Ceylon coast. These disks resemble Phyllactidium (Kützing, Tab. Phycol); but 
many of the minute cells contain bright rosy-red colouring matter. I know nothing of their development or repro- 
ductive organs. 
+ For the literature of Chroolepus conf. Rabenhorst, Flora Alg. Europ. р. 371 et seg., and Kutzing, Tab. Phycol 
91-97. | 
SECOND SERIES.—BOTANY, VOL. II. T 
