498 BOTANICAL GAZETTE [DECEMBER 
a 
Ptelea.—A revision of this genus as it occurs in western and southwestern 
United States and Mexico has heen published by Grrenr."3 Under his treat- 
ment the genus has become rich in species, 59 being recognized, of which 55 
are new. Three natural groups are defined, each with its own geographical 
range: (1) species (37) with chestnut-brown twigs and prevailingly glaucescent 
or bluish-green foliage; (2) species (13) with amost white twigs and yellow 
green foliage; (3) species (g) with cinnamon-colored twigs, a peculiar hue and 
venation of foliage, and narrow-winged or even wingless samaras.—J. M. C. 
Anatomy of Commelinaceae.—Hotim has published an elaborate memoir"4 
dealing chiefly with the general morphology and anatomy of the Commelinaceae. 
€ 17 species investigated represent the genera Commelina (5), Aneilema, 
Tinantia, Tradescantia (9), and Weldenia. The memoir is a mine of informa- 
tion which can be drawn upon by the future student of the group who is seeking 
to organize such details into general statements.—J. M. C. 
Genera Siphonogamarum.—The eighth fascicle of Datta Torre and 
Harms’s'S list of the genera of seed plants concludes the genera of Compositae, 
9629, Thamnoseris being the last one. The genera of uncertain affinity swell 
the number of genera to 9810. There is also a supplement of 51 pages, and 
the general index of names is begun.—J. M. C. 
NOTES FOR STUDENTS. 
Ancient Araucarians.—In Jurassic and Cretaceous deposits there occur 
abundant remains of leafy branches of coniferous plants that have been described 
under the generic name Brachyphyllum. The genus has been referred by various 
authors to Araucarineae, to Cupressineae, and to Taxodineae (near Sequoia) ; 
but in a recent paper by Jerrrey and Hotticx"® it is shown from an investi- 
gation of the internal structure that here can be no doubt as to its Araucarian 
affinities. In the same paper Protodammara is described as a new genus, to 
include certain Cretaceous cone scales that had been referred to the living genus 
Agathis (Dammara). Certain lignites associated with both Brachyphyllum 
and Protodammara were also found to be Araucarian; and the conclusion is 
reached that these lignites represent the wood of the trees which bore the leafy 
ENE, EDwarD L., The genus Ptelea in the western and southwestern 
United Stated and Mexico. Contrib. U. S. Nat. Herb. 10:49-79. 1906. 
14 Hotm, THEODORE, Commelinaceae. Morphological and anatomical studies of 
the vegetative organs of some North and Central American species. Memoirs Nat. 
Acad Sci. 10:159-192. pls. 1-8. 1906 
- Datta Torre, C. G. DE and Harms, H., Genera Siphonogamarum ad systema 
Englerianum conscripta. Fasc. 8. pp. 561-640. Leipzig: Wilhelm Engelmann. 
1906. M6. : 
+6 HOLLick, A., and JeFrrey, E. C., Affinities of certain Cretaceous plant remains 
commonly referred to the genera Dammara and Brachyphyllum. Amer. Nat. 40: 
189-215. pls. I-5. 1906. 
