72 KOYAL SOCIETY ()F CANADA 



collection from Prof. Prosser, as derived from the Chase formation 

 (Pennian) of Chase County, Kansas. 



Transverse. — Tracheids 47 x 47 mlc. broad, the walls 9.3 mic. thick. 



Radial. — Ray cells straight or abruptly narrowed at the ends, equal to 3-4 



tracheids; the lateral walls show no recognisable structure. 



Bordered pits in 1-3, chiefly 2 rows, hexagonal, 12.5 mic. broad. 

 Taiujeiitial. — Rays numerous, 1-seriate or 2-seriate in part, the broadly oval, 



thin-walled tells 28 mic. broad. 



COKDAITKS HAMir.TOXKNSi;, H. sp. • 



Figs. 2-7. 



An iindescribed species from tlie (ienesee sliales (Hamilton Group) 

 of Ontario Co., X.Y. Collected by Prof. J. :M. Clarke. Material in the 

 collection of Sir William Pawson. 



Tills speeiinen shov-. many interesting details of bark structure, 

 which serve to enlarge our knowledge of the general structure of these 

 plants. For the purposes of this description, and as represented by the 

 fossil, bnt without strict reference to the proper subdivisions of that 

 structiu'e, the bark may be divided into three zones, the inner, middle 

 and outer. In a transverse section the following details appear : — 



The inner zone (llg. 2) is composed of isodiametric, thin-walled 

 parenchyma elements. Scattered through this region, but chietiy fonn- 

 ing a limiting layer on the outer face, there are niunerous resin bearing 

 elements which in the latter situation assume much greater dimensions, 

 but the details of structure of which cannot be satisfactorily determined 

 owing to the alteration of parts. The. middle zone (tig. 3) consists of 

 radially elongated, thin-walled elements which simulate cork in their 

 tendency to disposition in radial series. Its radial extent is about equal 

 to or somewhat in excess of the inner zone. Throughout its entire 

 extent, rc.-^in canals of simple structure and of variable size, are distri- 

 buted in large numbers, and in some cases at least, they appear to be 

 derived from the main system of canals forming the outer limit of the 

 first, and the inner limits of the second zone. The outer bark is repre- 

 sented by a broad zone of structure in process of disintegration. This 

 is shown in part in fig. 4, which also includes the outer part of the 

 middle zone. 



The outer bark is represented by a broad zone of structure in pro- 

 cess of disintegration. This is shown in part in fig. 4, which also in- 

 cludes the outer part of the middle zone. 



