88 BOTANICAL GAZETTE [yULY 
A cretaceous genus of Abietineae.—Dr. Stoprs® has investigated a petri- 
fied tree trunk from the Cretaceous of New Zealand, which shows ‘‘a striking 
mixture of abietinean and araucarian characters.” She regards it as a new 
genus, which is named Planoxylon, and which is made to contain two species, 
the one investigated (P. Hectori) and another (P. Lindleii) that had been 
referred to Araucarioxylon by SEWARD. P. Hectorzis of special interest because 
“it comes from Australasia, where no Abietineae or Juniperineae or other 
forms with abietinean ray structure are endemic at present:’”’—J. M 
Morphology of Treubia.—Grtw,*» studying material of Treubia insignis 
Goebel from Tjibodas, finds that the thallus develops from a dolabrate apical 
cell like most of the anacrogynous Jungermanniales; that the archegonia 
occur in clusters of 8-10 and may have as many as 16 neck canal cells each; 
that only one sporophyte develops on each thallus; that vegetative reproduc- 
tion is by means of 3 or 4-celled brood bodies; that mycorhiza are present in 
the thallus; and that the chromosome numbers are 8 and 16.—W. J. G. 
LAND. 
Plagiochasma.—In a monograph of the genus Plagiochasma, EVANS” 
includes as much of the morphology of the group as will be useful for purposes 
of identification of species, gives a key to the North American species, and 
describes in detail the 6 species found in North America, one of which is new 
to science. The reviewer believes that several new species will be added to the 
group from Mexico when botanical exploration again becomes possible in that 
country.—W. J. G. LAnp. 
Endemism in the flora of New York.—Taytor* has found in the flora of 
the region near New York 22 endemic species, of which he considers 14 to be 
accounted for by generic or specific instability; 2 are “habitat endemics,” 
or habitat forms of more widely spread species; while 5 are evidently relic 
endemics. He is convinced, therefore, that many forces are operative in mak- 
ing endemics, and he gives some discussion of such possible forces.—GEO. D. 
FULLER. 
38 Stopes, Marte C., An early type of the Abietineae(?) from the Cretaceous of 
New Zealand. Ann. Wotuay 30:111-125. pl. 4. figs. 7. 1916. 
39 Grin, C., Monographische Studien an Treubia insignis Goebel. Flora 106: 
331-392. pls. 3-5. figs. 14. iy 
4 Evans, ALEXANDER W., The genus Pvp ane and its North American 
species. Bull. Torr. Bot. he 42:259-308. figs. 8. 1915. 
4t TayLtor, NoRMAN, Endemism in the flora of ae vicinity of New York. Torreya 
16:18-27. 1916. 
