THE EVOLUTION OF PLANTS 599 



connection. So closely does it resemble a certain fern 

 (Lomaria) that -the botanist Kunze, who first described it 

 when it was brought from Natal to the botanic garden at 

 Chelsea, England, supposed it was a fern, and named it 

 Lomaria eriopus. The specimen possessed no fruit, which 

 would have helped to identify it. Its leaves, with 

 circinate vernation, have a pinnately compound blade, 

 and leaflets with pinnate dichotomous venation. Two 

 or three years later another botanist, examining it more 

 closely, pronounced it a "fern-like Zamia or a Zamia-like 

 fern." These facts show how puzzling the specimen was, 

 and how closely a plant may resemble both a cycadophyte 

 and a fern. In a sense this plant may be called a living 

 fossil. Specimens have since come into flower in botanic 

 gardens, and the typical cycadaceous cones (Fig. 420) 

 leave no doubt that the plant is a true cycadophyte. 



518. Derivation of New Types. Attention should here 

 again be called to the fact that the theory of evolution does 

 not teach that one given species becomes transformed into 

 another, but simply that new species are descended from 

 older forms which may or may not continue to exist. It 

 is not supposed, for example, that ferns developed into 

 cycads, and cycads into higher gymnosperms, but that there 

 has been an unbroken line of descent (possibly more than 

 one) in the plant kingdom ; that closely related forms (like 

 ferns and cycads) have descended from a common ancestral 

 type which may or may not now be found. We must not, 

 in other words, expect necessarily to find in fossil forms the 

 direct ancestors of those now living, although a study of 

 their structure is of the greatest value in enabling us to 

 understand the genetic relationships of the great groups 

 of plants. 



