OF CENTRAL CANADA PART III. 



205 



of the Carboniferous beds. Among the cephalopods, however, genera 

 with angulated septa (bactrites, goniatites) make their appearance, 

 and thus foreshadow the advent of the more elaborately-lobed 'ypes 

 of the succeeding age. Of the higher vertebrates, mammalia and 

 birds are entirely unknown, and reptiles all but absent the only 

 undoubted examples of the latter occuring in Permian strata. The 

 remains of labyrinth odont amphibians, on the other hand, occur 

 throughout the Carboniferous and Permian formations. Rock-repre- 

 sentatives of the earlier Palaeozoic periods occur widely throughout 

 Ontario and Quebec. (Sse Parts Y. and VI.) 



(7) The succeeding strata, of Mesozoic age, are characterized 

 essentially by the remains of numerous extinct types of reptilia of 

 remarkable organization, including the paddle-footed Ichthyosaurians 

 and Plesiosaurians, the winged Pterodactyls, the Dinosaurs, and 

 many others. These strata are also especially distinguished by the 

 ammonites and other genera of tetrabranchiate cephalopods with 

 highly-lobed or foliated septa, which first appear in them, and which 

 are altogether unknown in higher formations. Of these, the am- 

 monite (as a genus) ranges throughout the entire Mesozoic series ; 

 the ceratite is confined to Triassic strata ; and the baculite, scaphite, 

 ancyloceras, crioceras, turrilite, &c., are essentially Cretaceous forms. 

 The belemnite, a genus of the dibranchiate cephalopoda, known by 

 its conical (internal) shell, is also especially characteristic of Mesozoic 

 strata. Among the representatives of fish-life, homocercal forms 

 appear ; and in the higher or Cretaceous portions of the series the 

 rapidly-diminishing ganoids become almost entirely replaced by 

 teleosteans of modern type. Vertebrates, higher than reptiles, are 

 exceedingly rare ; but some bird remains of apparently reptilian 

 character, referred to the extinct genus Archceopteryx (distinguished 

 by an elongated series of caudal vertebrae : an embryonic type of 

 structure as regards existing birds), have been found of late years in 

 Jurassic strata ; and the Cretaceous beds of Western America have 

 yielded some remarkable remains of toothed birds. A few small 

 jaws and teeth, belonging most probably to marsupial mammals, are 

 also known as Mesozoic forms. In the vegetation of the age, cycads 

 and conifers stand out as dominant types especially in its earlier 

 and middle periods ; but monocotyledons are also represented through- 

 out its series of strata, and dicotyledons appeared abundantly before 



