no THE CHAIN OF LIFE. 



sorts are so similar that no definite separation of them has 

 yet been made. Either these anomalous trees constitute a 

 link connecting the two great series of the vegetable kingdom, 

 or we have been confounding two distinct groups, owing to 

 imperfect information. 



Another curious, and till recently little understood, group 

 of Carboniferous trees is that known as Cordaitesj which 

 existed already in some of its species in the Devonian. Their 

 leaves are long, and often broad as well, and with numerous 

 delicate parallel veins, resembling in this the leaves of grasses. 

 Corda long ago showed that one species at least has a stem 

 allied to the Club-mosses. More recently Grand' Eury has 

 found in the South of France admirably preserved specimens, 

 which show that others more resembled in their structure the 

 Pines and Yews, and were probably Gymnosperms, approaching 

 to the Pines, but with very peculiar and exceptional foliage, of 

 which the only modern examples are the broad-leaved Pines of 

 the genus Dammara (Frontispiece to Chapter). Here again 

 we have either two very distinct groups, combined through 

 our ignorance, or a connecting link between the Lycopods and 

 the Pines. 



The Yews and their allies among modern trees, while mem- 

 bers of the great Cone-bearing order, bear nut-like seeds in 

 fleshy envelopes, sometimes, as in the Ginkgo of Japan, consti- 

 tuting edible fruits. Seeds of this type seem to have been 

 extremely abundant in the Carboniferous age in all parts of 

 the world, and were probably produced by trees of several 

 genera {Dadoxylon^ Sigillaria, Cordaites, etc.) (Fig. loo). 

 Charles Brongniart has recently described no less than seven- 

 teen genera of these seeds from the coal-field of St. Etienne 

 alone, and it would be a low estimate to say that we probably 

 know as many as sixty or seventy species in all, while the 

 trunks of great coniferous trees allied to Taxineae, and 

 showing well-preserved structure, are by no means uncommon 

 in the Devonian and Carboniferous. Had these great Yews 



