[1-ENiuM.ow] XOKTH AMKKK'AN SPECIES OF DADOXYLON 68 



only four. The slit-lilvc orifice is diagonal and nearly the full diameter 

 of tlie pit. The most charticU'ristic feature \f. to be found iu the 

 peculiar distribution of the Ijordered pit-s, which occur in well defined 

 groups of about 6-13, while the groups themselves fall into radial series. 

 These facts were correctly noted by Dudley,' but they have been entirely 

 unnoticed by Dawson- and also of Knowlton,^' whoso diagnosis of this 

 species is simply compiled from that of Dawson. The character is 

 nevertheless to important one (fig. 12), since it is tlie one feature which 

 alone, will differentiate this species from all others. In a tangential 

 section, the rays are seen to he numerous, 1-2, more rarely 2-seriate, 

 and varying from 24-55 mic. in width. The oval or roun,d cells are all 

 thin wiilled. From these facts the following diagnosis may be derived : 

 Transverse.— Tr^cheids about 44 x 55 mic, the walls about 12.5 mic. thick. 

 Radial.— Ray cells resinous and starch bearing, long and narrow, about equal 



to 3-7 tracheids, the ends conspicuously narrower; the pits on the 



lateral walls 3-6, chiefly 4 per tracheid, the slit-lilie orifice nearly the 



full diameter of the pit. 



Bordered pits numerous, round, about 9.3 r.iic. broad, distributed 



in radially disposed groups of about 6-13; the orifice diagonal, nearly 



the diameter of the pit. 



Tan!;ential.—Ra.yB of medium height, 1-2, rarely 3-seriate in part; from 24-55 

 mic. broad, the oval or round cells all thin walled. 



CORDAITKS C'LARKir, Dn. 

 Figs. 8, 16. 



Bib. :— Dawson, Foss. PI. of the Dev. & U. Sil. Form, of Canada, 18S2, 125; 



Knowlton, Proc. U. S. Nat. Miis., XII., 607. 

 Dist.— Hamilton Group, Ithaca, New York. 



This sijecies was founded upon material obtained from the Genesee 

 shales at Lake Caiiflndaigua, Xew York, by Prof. II. M. Clarke, and was 

 first recorded by Sir William Dawson in 1882.* 



The material in my hands shows a well developed pith composed 

 of large, thin-walled cells, many of which contain starch. There is 

 also evidence of an abundance of resin which is iappai-ently contained 

 in specialised cells, but this fact could not be ascertained satisfactorily. 

 In a transverse section the elements of the protoxylem are not specially 

 different iated from those of the surrounding tracheids which show the 



• Jn'l Cincin. Soc. Nat. Hist., 1889, 54-55. 

 ' Geol. Surv. Can., 1871, 14. 



' Proc. U. S. Nat. Mus., XII., 606. ! 



* Foss. PI. of the Dev. & U. Sil. of Can., 1882, 125. .j 



S-c. IV., 1000. ,5. 



