AS COMPARED WITH THAT OF THE PRESENT DAY. 423 



* 



inclined to regard the species of Halonia as roots of Lepidodendron, on 

 which opinion I have no remarks to offer. 



Nearly forty species of Lepidodendron are described ; and the cha- 

 racters of the majority of them are drawn from the arrangement and 

 form of the scars on the stem. There are, besides, seven or eight 

 species of Lepidostrobus, some of which (perhaps all) are parts of one 

 or other of the Lepidodendrons. Halonia, another genus of the Lepi- 

 dodendreai, is composed of three species, possibly the roots of these or 

 others of the same genus. Some Lepidophylla are certainly its leaves : 

 a few of the carboniferous Lycopodites are founded on its slender ter- 

 minal branches ; and one or more Trigonocarpi (as I shall show in some 

 remarks upon Lepidostrobus) are probably the seed-vessels (sporangia) 

 of the same. 



This reduction of genera to species, and in some cases of genera 

 contained in one order (as Trigonocarpum, which is placed in Scitami- 

 nea by Unger) to the species of another, materially diminishes our ideas 

 of the great amount of species preserved in the coal. Such a reunion 

 is not, however, available in practice, nor is it here for the first time 

 forced on our attention ; though it is not sufficiently considered, in the 

 hurry of describing new forms, that the result of further discoveries 

 amongst those already described, is to reduce the many supposed 

 species to fragments of a few certain ones. Hence, the object of the 

 fossil botanist should be now, in preference to describing what appear 

 new species, and thus increasing the synonomy, to throw more light 

 on the old, about all of which we know, botanically speaking, very 

 little. 



But it is not merely by the reduction of genera, founded on the parts 

 of plants, that this is to be carried into effect. No one accustomed to 

 study existing individuals, can regard the characters adopted for dis- 

 tinguishing the Lepidodendrons, without comparing their validity with 

 those drawn from the same parts of their living analogues. Applying 

 this rule to Lepidodendron, it will be seen that if the species of that 

 genus were as prone to vary in the foliage as are those of Lycopodium, 

 our available means for distinguishing them are wholly insufficient. 

 Take, for example, the noblest of the genus Lycopodium, the L. densum 

 of New Zealand, which in stature, and probably in general habit, &c, 

 approaches nearer to Lepidodendron than any of its congeners. In this 

 species, not only do the shape and arrangement of the leaves vary in 

 different specimens, but leaves from different parts of the same indi- 

 vidual are very unlike. The three accompanying cuts represent as 

 many states or varieties of this plant, gathered by myself in New Zea- 

 land, where multitudes of specimens of all were growing intermixed. 

 Of these, the dense fastigiate one (Fig. 12) is the most common ; and 



