JEFFREY: NEW PREPINUS. 337 
Conclusions. 
It is clear from the foregoing account that there was present in the 
flora, entombed in the Lower Cretaceous clays of Gay Head, Martha's 
Vineyard, jNlassachusetts, a species of the genus Prepinus, differing 
c-learly from the similar remains found at Kreischerville, Staten Island, 
New York. This need supply no argument against the general 
stratigraphic equivalence of the Cretaceous deposits of the two locali- 
ties, which has been insisted upon by both Ward and Hollick. There 
are likewise specific differences between the supposed Sequoias and 
Dammaras of the two deposits as is shown in the literature. 
It will not be out of place at the present time to discuss the general 
problem of the relative antiquity of the two main divisions of the Abie- 
tineae. It is quite generally assumed that those Abietineae which are 
without resin canals in their secondary wood are of greater antiquity 
than those which possess them. Against this view it has been urged 
by the present writer, that there is clear evidence that those Abietineous 
Conifers, which are characterized by the possession of short-shoots and 
both horizontal and ligneous resin canals, are of more ancient origin. 
The genus Prepinus, judged by the criteria universally accepted as 
demonstrating phylogenetic antiquity must be regarded as a very 
ancient representative of the Conifers, for it has a type of leaf organiza- 
tion found elsewhere only in the Cordaitales, which became extinct 
at the end of the Paleozoic period. Moreover, the presence of crypto- 
gamic wood in the leaf-traces of this genus makes its closer affinity with 
the older Gymnosperms beyond reasonable ciuestion, in the present 
state of our knowledge. The experimental data derived from wound- 
ing and the recapitulationary phenomena observed in the first annual 
ring of growth in the Abies-like representatives of the Abietineae 
further strengthen the position occupied by the writer, by making it 
clear that the Abieteae have come from ancestors possessing the ligne- 
ous characters of the Pineae and are consequently of later origin. 
If, as seems inevitable from the evidence now at our disposal, we 
regard the Pineae as the oldest representatives of the Abietineae, the 
question arises, whether the resin canals which are a constant feature 
of structure of the wood of this subtribe, originated first in the horizon- 
tal or the vertical plane. Gothan has recently expressed himself 
strongly in opposition to the writer's views as to the antiquity of the 
