` HOOKER LECTURE, 1022. 225 
Costa Rica—rich in endemic forms—, in the West Indies, along the Andes to 
the Falkland Islands, on the heaths of Ruwenzori up to over 10,000 ft., from 
Natal to Table Mountain, in Madagascar, in the Island of Réunion, on 
Amsterdam Island, in New Guinea where Dr. Wollaston tells me that he 
collected several species, some growing at an altitude of over 12,000 ft., in 
New Caledonia where Prof. Compton recently found at a height of 8000 ft. 
one of the largest species of the genus, in New Zealand, and as far north as 
Hawaii, in India, China, Japan, and the Philippine Islands, The absence of 
Gleichenia from Northern Africa, the whole of Europe, Western Asia, and 
practically the whole of the North American continent is a surprising fact. 
To this geographical distribution the fossil record affords a striking contrast. 
It has long been a palæobotanical commonplace that in the Cretaceous 
epoch the vegetation of West Greenland would appear to have been sub- 
tropical ; in other words, the plants found in the freshwater sediments exposed 
on the east coast of Disco Island and in the ravines of the mainland, 300 miles 
north of the Arctic circle, are in sharp contrast to the vegetation which now 
flourishes in the short but concentrated summer on the margin of the ancient 
Greenland plateau buried under an ice-sheet of unknown depth. Twice only 
have I collected fronds of the Fern Gleichenia: on the edge of a Malayan 
forest where it luxuriates under a tropical climate, and from sediments 
deposited in a delta or inland lake on the submerged fringe of Cretaceous 
Greenland. The apparent identity of the living and the dead gives reality to 
Carpenter’s aphorism “ we are still living in the Cretaceous period.” Hooker 
in one of his letters expressed the opinion that “ Geology gives no evidence 
of a progression in plants," and adds * I do not say that this is proof of there 
never having been a progression—that is quite a different matter--but the 
fact that there is less structural difference between the recognisable repre- 
sentatives of Conifers, Cycadeæ, Lycopodiaceæ, ete., and Dicotyledons of the 
Chalk and those of present day than between the animals of those periods 
and their living representatives, appears to me a very remarkable fact.” 
It is easy to speak of the “first appearance" of certain plant types, but 
actually to trace to its source any family or group is a problem that seems to 
remain insoluble. The search for origins has much in common with the 
quest of the Holy Grail. The unfolding of plant-life viewed through the 
distorting mists over the successive stages of earth-history takes the form of 
a series of outbursts of energy—the records of one period tell us nothing, 
while those of the next reveal a fresh type of vegetation, or it may be a 
single genus in possession of widely scattered regions of the world. 
Whatever the process of untolding may have been, we seem unable to do 
tnore than observe the completed results ; the beginnings are hidden from 
us, and the farther we penetrate into the past the farther into the distance 
recedes the object of our search. 
The genus Oligocarpia, founded on fern-like fronds from the Coal 
