74 Elkins and Wieland — On Devonian Wood. 



bonized aggregations not infrequent in petrified wood.* Of 

 course the exigencies of silicification must be fully taken into 

 account, but doubtless the resinous character of the bodies here 

 described can be definitely established after various well con- 

 served fossil species have been fully and thoroughly studied. 



Certain of the tracheids also contain dark silicified bodies, 

 which appear to be of resinous origin (cf. r in figures 2 and 3). 



In 1900 Professor Penhallow of McGill University published 

 an interesting and suggestive account of the Dadoxylon species 

 of North America. In this paper he describes a species, — 

 Cordaites Newberryi — which was discovered in the Middle 

 Devonian of Ohio by Dr. Newberry and in the Carboniferous 

 of Ohio by Claypole. The species from the Indiana Black 

 Shale, as described above, bears a striking resemblance to 

 Cordaites Newberryi. However there are several clear varia- 

 tions. Before quoting from Penhallow's account, which is the 

 most complete, I may refer to several brief earlier accounts of 

 this species. 



Dawson merely describes Dadoxylon Newberryi as having 

 areoles (pits) in two or three rows with large oblique pores and 

 numerous rays made up of eighteen rows of narrow cells 

 in two series.f Later he describes carbonized or silicified 

 trunks from the Hamilton of New York having hexagonal 

 areoles with oval pores.J Newberry gives a much more 

 definite description ; he states that the wood cells are quad- 

 rangular; the largest diameter noted, •04-'05 mm ; the thickness 

 of the wall, *01 mm ; the length of the ray cell, 4-5 times the 

 diameter ; the terminal walls are oblique ; the areoles are in 

 groups of one to three rows; the pores are elliptical and 

 obliquely inclined ; the areole diameter is -01 mm . The rays are 

 single or double in width and consist of from one to twenty 

 superposed cells. Nearly all the ray cells contain globules of 

 resinous matter. § Penhallow's description agrees in general 

 with that of Newberry, but Penhallow emphasizes a character 

 which is the important and distinguishing feature of this 

 species, namely the arrangement of the pits in radial bands and 

 hence in definite groups of pits, 6 to 13 in number, in each 

 tracheid. Newberry mentions the pit groups without emphasis 

 and fails to note the radial band. Penhallow in reference to 

 the growth rings says: " In a radial extent of 17 millimeters, 

 this species shows no evidence of growth rings." 



* Jeffrey, E. C, A New Araucariau Genus from the Triassic " Wood- 

 worthia Arizonica." Proc. Boston Soc. Nat. Hist., vol. 34, No. 9, July, 1910. 



f Dawson, J. W., Fossil Land Plants of the Devonian and Upper Silurian. 

 Geol. Surv. of Canada, 1871. 



% Dawson, J. W\, Fossil Plants of Erian (Devonian) and Upper Silurian 

 Formations of Canada. Geol. Surv. of Canada, Pt. II, 1882. 



§ Newberry, J. S., Devonian Plants from Ohio. Jour. Cincinnati Soc. Nat. 

 Hist., vol. xii, pp. 48-56, 1889. 



