150 GEOLOGICAL DISTRIBUTION. 



transition form between the true ganoids and the lung-flshes. A 

 similar position is occupied by some of the other crossopterygian 

 fishes of the period, as Dipterus. 



Caxboniferous Fauna. — The life of the Carboniferous period is 

 marked by two important features: 1. The introduction for the first 

 time of vertebrate animal forms higher in the scale of organisation 

 than the fishes, i. e., the amphibians; and 3. The great develop- 

 ment of strictly air-breathing or terrestrial animals. Of these last 

 we have at least four distinct types indicated — ^the Gasteropoda, 

 Insecta, Arachnida, and Myriapoda. Of the first, which have a 

 solitary forerunner in the Devonian formation, we are acquainted 

 with a comparatively limited number of forms (Pupa, Anthraco- 

 pupa, Dawsonella, Zonites), all of them more or less closely related 

 to forms still living at the present day. The insects comprise not 

 only members of the low order of netted-veins, which are the only 

 forms known to be represented in the Devonian deposits, but those 

 of the more highly organised Orthoptera, and not improbably also 

 Coleoptera (beetles), although most of the remains referred to the 

 latter order are now positively known not to belong there. The 

 Orthoptera comprise, among other forms, some sixty or more spe- 

 cies of primitive cockroach, the Palseoblattarise, which may be con- 

 sidered to represent the ancestral type of the modern social pest 

 (Blatta), whose earliest appearance dates from the Triassic period. 

 To the same order belong the giant walking-sticks recently brought 

 to light from the coal-measures of France, the Titanophasma Fayol- 

 lei, which measure in length (in one specimen) upwards of twelve 

 inches, and are, therefore, by linear measure, very nearly the largest 

 of recent as well as fossil insects. 



This extraordinary development of a form, which may be taken 

 to represent the extreme term of specialisation in an insect, in a 

 period so early as the Carboniferous, is certainly not a little re- 

 markable, and argues very strongly for the great antiquity beyond 

 its own period of the origin of this class of animals. It is also not 

 a little surprising that no representatives of the family of walking- 

 sticks (Phasmida), other than those found in the Carboniferous 

 deposits of France — Titanophasma and Protophasma — have as yet 

 been found in a fossil condition, except such as may have been 

 preserved in amber. Of the Neuroptera, the Haplophlebium Bar- 

 ncsii, from Nova Scotia, attained an expanse of wing of seven 



