February 22, 1907] 



SCIENCE 



293 



or other parts in whicli the plant tissue 

 is sufficiently well preserved for sectioning 

 and microscopic examination, the ordinal, 

 or family, or even exact generic I'elation- 

 ships may be accurately determined. 



Such conditions of preservation have 

 been found in the Cretaceous deposits at 

 Kreischerville, on Staten Island, and a 

 large amount of material from this locality 

 has been collected and subjected to critical 

 examination. Some of the preliminary re- 

 sults thus obtained form the basis of this 

 communication. 



The lantern slides show microscopic en- 

 largements of cones of Protodammara, sec- 

 tions of the wood of Brachyphyllum and 

 other gymnosperms, demonstrating their 

 Araucarineous affinities, and sections of 

 Pityoreylon with resin canals, indicating 

 the probable sources of the amber which 

 is abundant in the deposits. 



Some Vestigial Characters in the Cone of 

 Pines: Professor E. C. Jeffrey, Har- 

 vard University. 



Classification of the Genus Panicum: A. S. 



Hitchcock, U. S. Dept. of Agriculture. 



In the comprehensive works of Bentham 

 and Hooker (Gen. PI.) and Engler and 

 Prantl (PI. Fam.) the large genus Panicum 

 was divided into a number of sections, 

 such as Digitaria, Trichachne, Thrasya, 

 Echinochloa, Hymenachne, Ptychophylhim, 

 and Eupanicum. Most of these sections 

 may more conveniently be considered as 

 genera, this division being based upcoi well- 

 marked characters of both structure and 

 habit. Retaining the name Panicum for 

 most of what has been included in the sec- 

 tion Eupanicum, this genus may again be 

 divided into groups, of which the following 

 are American : Bamileta, Fasciculata, Pros- 

 trata, Agrostoidia, Laxa, Maxima, Brevi- 

 folia. Verrucosa, CapUlaria, Prolifera, 

 Dichotoma, Parvifolia, Virgata, Diffusa, 



Divaricata [Sect. Lasiacis]. These names 

 should not be considered as sectional 

 names. They are merely group names 

 formed from a well-known specific name of 

 each group. Ptychophyllum and Lasiacis 

 should probably be assigned generic rank. 

 The group Dichotoma, which includes about 

 one hundred closely allied species of the 

 southeastern United States, can again be 

 divided into a number of subgroups, the 

 classification being based upon habit, size 

 and pubescence of skelatils, ligner, pubes- 

 cence of culms, sheaths and blades, and the 

 manner of branching of the fall culms. 

 These groups are: Depau-perata, Laxiflora, 

 Angustifolia, Eudichotoma, Nitida, Lanu^ 

 ginosa, Unciphylla, Eusifolia,Sph(Erocarpa, 

 Corurnutata, Lancearia, Oligosanthia, Sco- 

 paria, Latifolia. 



Duncan S. Johnson, 



Secretary 

 The Johns Hopkins Univeksitt 



THE AMERICAN ASSOCIATION FOB THE 



ADVANCEMENT OF SCIENCE 



MEETING OF SECTION E— GEOLOGY AND 



GEOGRAPHY 



On account of the special meeting of the 

 association at Ithaca in July, 1906, at 

 which Section E had a full program of 

 papers and excursions, no effort was made 

 to get papers for the New York meeting of 

 the association. Some fifteen papers, how- 

 ever, were spontaneously offered in addi- 

 tion to the vice-presidential address, and 

 Section E held four sessions during the 

 New York meeting. 



At the session for organization held at 

 Schermerhorn Hall, Columbia University, 

 directly after the adjournment of the first 

 general session of the association on De- 

 cember 27, Professor J. B. Woodworth, of 

 Harvard University, was elected a member 

 of the sectional committee for the term of 

 five years. Professor N. M. Fenneman was 

 elected a member of the general committee, 



