3 



questions raised by this and the other specimens demanded 

 a more detailed investigation ; and I now wish to base on 

 this, and the other specimens above referred to, some gene- 

 ral remarks on our present knowledge of Palaeozoic 

 Gymnosperms, and more especially on those of North 

 America. 



Mr. Lacoe's large specimen, for which I have proposed the 

 generic name Dictyo-cordaites in reference to its peculiar 

 netted venation, may be described as follows l : 



DIOTTO-OORDAITES I/Acoi, Dawson. (Fig. 1) 



The specimen is a branch or small stem 2 \ cm. in diameter 

 and 46 cm. in total length- It is flattened and pyritised, 

 and shows, under the microscope, only obscure indications 

 of the minute structure, which would seem to have consisted 

 of a pith surrounded by a fibrous envelope and a bark of no 

 great thickness. It would appear, therefore, to be exogenous 

 with a thin woody cylinder and large pith. The stem shows 

 portions of about 15 leaves, which have been at least 16 cm. 

 long and 3 to 4 cm. broad. They are spirally arranged and 

 are decurrent, apparently by a broad base, on the . stem. 

 Their distal extremities are seen in a few cases, but in all 

 seem injured by mechanical abrasion or decay. It seems 

 most probable that they were truncate and uneven at their 

 extremities. The stem is terminated by a cluster or com- 

 pound corymb of spikes of which 20 are seen. They are 

 slender, but seem to have been stiff and woody, and the lar- 

 gest are about 15 cm. in length. The peduncles are knot- 

 ted and wavy in outline, as if dry and woody in texture 

 when recent. In this they differ from most of the ordinary 

 Antholites, but agree with my A. Devonicus,' 2 and also with 

 A. rhabdocarpi of the Carboniferous 3 which they resemble 

 in the form and arrangement of the fruit. They have short 



1 I am indebted to Professor Penhallow, of McGill University, 

 for his kind aid in the study of the specimen. 



2 Fossil Plants of Devonian and Upper Silurian, 1871, Plate XIX. 



3 Journal London Geological Society, 1867, Plate VII. 



