04 BOTANICAL GAZETTE [AUGUST 
cone scales. If this plant really is, as the authors think, an abietin- 
ean in process of transformation, it would appear to be a question 
whether it were headed toward Ginkgo, which it resembles in 
external features, or toward an araucarian, which it does not 
resemble externally and toward which it has made but a very small 
beginning structurally. 
In 1908 Prepinus was described (37). The name was proposed 
“for this type in the belief that it is the direct ancestor of Pinus.” 
“‘It is characterized by the possession of short shoots or brachy- 
blasts of a generalized type, which were deciduous, but bore numer- 
ous spirally arranged instead of few verticillate fascicular leaves.” 
‘The leaves attached to the brachyblasts differed from the fascicular 
leaves of Pinus in having their paired resin canals continuous to the 
very base. The leaves further possessed well marked centripetal 
xylem. About the foliar bundles was present a complicated double 
sheath of transfusion tissue closely related to the centrifugal wood 
and resembling that found in certain of the Cordaitales.” ‘‘Many 
of the true pines of the Cretaceous possessed the same double 
transfusion sheath as is found in Prepinus, but entirely lacked the 
centripetal wood which is characteristic of that genus.” ‘‘The 
elongated pitted elements described by WorsDELL and others on the 
ventral side of the protoxylem in existing coniferous leaves appear 
rather to be the relics of the inner transfusion sheath, which is a 
feature of cretaceous pines, than of true centripetal xylem.” 
From the resemblance of the leaf structure to certain Cordaitales, 
the conclusion is reached that the Abietineae are “‘a very old, if not 
the oldest, family of the Coniferales.” From this argument, and 
others already detailed, it is concluded that “‘the Abietineae must 
be considered more primitive than the Araucarineae.’”? What at 
first sight appears to be a new argument in support of this con- 
. tention is introduced in this paper. ‘‘The pitting of the older 
Araucarineae, which still survived in the Middle Cretaceous, showed 
a marked deviation from that found in Agathis and Araucaria, and 
a transition toward the type of pitting found in the Abietineae, 
while the oldest structurally known type of the Abietineae (Pre- 
pinus) shows no tendency whatever toward the araucarian type of 
bordered pits.”” There is, however, nothing new in this statement, 
