FLORA OF THE DEVONIAN. 



545 



in their young state, as represented in Fig. 190 a, wore often of % 

 regularly oblong form. They have numerous equal parallel nervines, 

 which were probably fibro-vascular, like those of Ferns, ai they 

 present precisely the same appearance as the ncrvures of the plants 

 of this family preserved with them, and which, in these beautiful 

 graphitized specimens, are traced in deeper lines of graphite than 

 the film of the same material which represents the intervening 

 parenchyma. In the best preserved specimens, the leaf is quite 

 smooth ; but in some the space between the nervures rises into little 

 ridges, so as to give a striated appearance. These different aspects, 

 however, often occur on different portions of the same leaf. The 

 present species so closely resembles C. borassifolia of the Coal 

 formation that it might readily be mistaken for it; but it differs 

 somewhat in the form of the leaf, and still more in the venation, 

 the nervures in the present species being perfectly equal* 



In the paper already referred to, I have stated at length my reasons 

 for preferring, in the case of this plant and C. borassifolia, the generic 

 name Cordaites, to Poacites, Flabellaria, and Naiggerathia, all of 

 which have been applied to such plants, together with others having 

 no affinity to them. To the name Pychnophyllum, proposed by 

 Brongniart, this objection does not apply ; but Cordaites, I believe, 

 has priority, and is due to the describer of the typical species. 



I associate the genus Cordaites with Lycopodiaceous plants with- 

 out hesitation, notwithstanding the peculiar character of its foliage, 

 because Corda has shown that its stem is strictly acrogenous in 

 structure, and of the same type with those of Lomatofloyos and 

 Ulodendron — a fact which excludes it alike from association with 

 Monocotyledonous plants and with Ferns. (See Chap. XX., supra.) 



It is worthy of notice that, while the leaves of Cordaites, unlike 

 those of Sigillaria and Lcpidodendron, were not attached by narrow 

 bases, but clasping, they were still, like those of nearly all other 

 Devonian and Carboniferous plants, deciduous and capable of 

 disarticulation, as is proved by the immense abundance of fallen 

 leaves, while the stems, probably remaining attached to the soil, 

 are rare. It is further to be observed that these leaves were rigid, 

 and long resisted decomposition ; on which account, no doubt, they 

 formed a favourite base of attachment for the little Spirorbes which 

 swarmed both in the Devonian and Carboniferous Periods. At St 

 John, many of these leaves are covered with these little shells. 



* The ncrvures in C. borassifolia are alternately thick and thin ; hut there is 

 another species in the Upper Coal measures of Nova Scotia which lias equal 

 nervures. 



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