235 
Pteridosperms and Angiosperms. 
Coal-Measures bearing abundance of fructification. He did this as 
the rarity of the occurrence had led him to suggest, at a previous 
sitting of the section, that in these latitudes the ferns of the coal¬ 
beds did not fructify on account of the low temperature in which 
they existed 1 .” Stur went much further and definitely excluded a 
large number of genera of foliage from amongst the ferns proper 
(1883). Then came the anatomical investigation of the vegetative 
organs of these forms, and the establishment of a provisional group, 
the Cycadofilices. depending on the anatomical characters. Finally,, 
seeds were discovered with tell-tale fragments of cycadofilicinean. 
fronds attached, thus proving the existence of a remarkable class 
of seed-plants now known as the Pteridospermeae. 
Could a Botanist have seen these plants growing side by side 
with cryptogamic ferns, no essential difference in habit would have 
been apparent; merely the existence of a reproductive peculiarity. 
The difference between them was analogous to that which we now 
find between ordinary seed-plants and certain of the Mangroves 
which are viviparous. The difference here is a trivial reproductive 
modification to be correlated with a special type of habitat, as is 
currently supposed. But it is just conceivable that this modification 
might become important in certain eventualities. However, the 
point to be noted is that seed-bearing at its inception was effected 
without marked change in the habit of the plants participating. 
By the use of the words “ at its inception ” it will not be understood 
that Pteridosperms have stood still. The Lagenostomas, Trigono- 
carpons, and other seeds that belong to the Pteridosperms are 
fairly advanced structures of the same order of specialisation as 
those of living Cycads, for instance. Exactly how these seeds were 
fashioned out of the ancestral sporangia there is no available direct 
evidence to tell us. The examination of petrified specimens shews 
them to be complicated structures—with their pollen-chambers, 
integuments and vascular systems—hardly paralleled in living 
plants outside the Cycad group. This early complexity may well have 
been an essential factor in the success of this rather momentous 
new departure, for it seems to have secured the conditions for 
fertilization in which the necessary water was under control. To 
state the matter in a slightly different form, plants that had acquired 
the seed-habit must have been able to spread to places other than 
such as provided the necessary conditions for the ordinary crypto¬ 
gamic type of fertilization, an advantage emphasized at the present 
1 Henfrey’s Botanical Gazette, Vol. I. (1849), p. 305. 
