1893.] Cretaceous Plant Population. 343 
wood timber. Further study of the sea-shore is needed along 
this line. But, apart from the testimony of the limited obser- 
vation, it appears demonstrable that the coast-line, simply 
because it was peripheral, thus terminating ejections, must have 
developed a tension-line group of plants in Cretaceous times. 
That. this tension-line was a relatively narrow one is proved 
by the great preponderance of metaspermic remains. For if it 
had been a broad one, the competition between older ferns and 
cycads, and newer metaspermic plants would doubtless have 
been sufficient to have brought down to the coast in larger 
numbers the more inland types of plants. 
The picture of the Cretaceous plant physiognomy which 
these considerations brings before our eyes is of a great solid 
inland forest of conifers, cycads, ferns, and Calamites (?), bounded 
by a thin peripheral line of metaspermic trees, shrubs and 
herbs. This peripheral line extended up both sides of all 
estuaries, streams and rivers, and thus shut off the older, luxu- 
riant and dominant flora from proper representation in the 
rocks of the period, as they have come down to us. An occa- 
sional inland plant was carried down some river and buried in 
the sands or shales at 1ts mouth, and sometimes when the shores 
were high the inland types came close to the sea, and in the 
Sequoias, Cunninghamites, A bietites, Zamieites and other genera 
of the Cretaceous rocks, we derive a hint of the inland and 
general character of the plant population. The very fact, 
therefore, of the high metaspermic preponderance in the fos- 
sils—since it shows metaspermic plants to have been uniformly 
the coast population, and hence the tension-line population, is 
an argument in favor of supposing that metaspermic plants 
were actually very much less predominant in the general flora 
then than they were in Tertiary or Recent time. 
Together with this disposition of the oft-repeated declaration 
that the Cretaceous Metasperme appeared with inexplicable 
suddenness, it will be seen that the other difficulty of their 
rapid and inordinate multiplication of species and genera is 
solyed—so far as such notes constitute a solution. The tension- 
line position, with its tremendous increase of urgency to mod- 
ify, and its concomitant increase of individual plasticity, 
