294 THE ZOOLOGIST. 



or mammal."* Prof. Geikie describes it as "marked by a 

 singular monotony of character all over the world from the 

 Equator into the Arctic Circle, the same genera, and sometimes 

 even the same species, appearing to have ranged over the whole 

 surface of the globe. It consisted almost entirely of vascular 

 cryptogams, and pre-eminently of Equisetacece, Lycopodiacece, and 

 Ferns. Though referable to existing groups, the plants pre- 

 sented many remarkable differences from their living representa- 

 tives. In particular, save in the case of the ferns, they much 

 exceeded in size any forms of the present vegetable world to 

 which they can be assimilated. Our modern horse-tails had 

 their allies in huge trees among the Carboniferous jungles, and 

 the familiar club-moss of our hills, now a low-creeping plant, 

 was represented by tall- stemmed Lepidodendra that rose fifty 

 feet or more into the air. The ferns, however, present no such 

 contrast to forms still living. On the contrary, they often recall 

 modern genera, which they resemble not merely in general 

 aspect, but even in their circinnate vernation and fructification. 

 With the exception of a few tree-ferns, they seem to have been 

 all low-growing plants, and perhaps were to some extent epi- 

 phytic upon the larger vegetation of the lagoons."! Now, if we 

 keep in mind this description of the very different flora that then 

 existed, we cannot help recognizing the fact that these Stick- 

 insects would either have a totally different relation to the trunks 

 of those tree-ferns to what they bear to the branches and twigs of 

 trees as known to ourselves, or that they then — as is more 

 probable — by a difference of form to their present descendants, 

 assimilated to their then environment. 



Again, the more ancient existence of the Phasmidce, prior to 

 the Carboniferous epoch, is implied, for it is impossible to 

 imagine on any evolutionary principle that these giant insects 

 came suddenly into existence at that era, especially if, as we 

 believe, their imitative structure is due to the action of natural 

 selection. In that case there must have been antecedently less 

 specialized forms, less imitative structure. " Considering the 

 abundance of Walking-sticks in Paleozoic rocks, the absence of 



* ' History of Creation,' 4th ed. vol. ii. p. 123. 

 f < Text-Book of Geology,' pp. 724-5. 



