1904] ‘JEFFREY—A FOSSIL SEQUOIA 329 
Tangential—Rays of one kind only in uninjured parts of the wood. Fusi- 
form rays present with linear rays in the case of injury and varying greatly in size. 
Fusiform rays when present generally with central resin canal, which is often 
occluded by tyloses. Linear rays varying greatly in depth. No pits on the 
tangential walls of the spring tracheids. Pits on the tangential walls of the 
summer tracheids numerous, generally not in rows. 
CONCLUSIONS. 
The greatest interest connected with the study of any extinct 
species is the light it throws on the structure and relationships of 
- livingforms. In the case of Sequoia Penhallowii the first point in this 
connection is its affinity with the living species of the genus. The 
very regular rings of growth and the very thin summer wood find 
their nearest parallel in S. gigantea. It is possible, however, that 
this similarity in structure of the wood may be due only to a similar 
mountainous habitat, since such surroundings tend, as is well known, 
0 produce regular growth rings in living trees. For example, wood 
of spruce grown at high altitudes is particularly fitted for turning 
and the manufacture of fiddles on account of the regularity of the 
annual rings, The narrowness of the zone of summer wood, how- 
“vet, cannot be explained in this fashion. The long narrow resin 
cells of the wood in our species also most nearly resemble those of 
5. siganiea. The wide spring tracheids with their double rows of 
radial pits present a feature of resemblance to S. sempervirens rather 
than > S. gigantea; but this feature cannot be regarded as conclusive, 
since in some of the fossil Sequoias known only by impressions the 
larger free leaves of the S. sempervirens type were correlated with 
— likes those of S. gigantea. The greater transpiration thus 
ig may well have been provided for by broader and sities 
_ netously pitted tracheids. A very strong argument for the associa- 
Hon of mt Species with S. gigantea is the fact of their similarity of 
ea distribution, for the fossil under discussion came from 
Mas of the Sierra Nevada Mountains, which are the home of the 
Py ; preenien. The weight of evidence seems to point to Sequowa 
ee ; being somewhat more closely allied to S. gigantea than 
bervirens, 
the od new turn to the question of the light which the study of 
Species throws on the general problem of the phylogeny 
