PAL.EONISCIAN PERIOD. 177 



Heteropoda 10 



Cephalopoda 69 



Trilobites 8 



Annulosa 6 



Fishes A few, especially of 



the genera Megalichthys and Holoptychius. 



Freshwater life is probably indicated, rather than fully illus- 

 trated, by several of the fishes, as Megalichthys the Unionidae 

 and certain tribes of fossil plants, as Equisetacese ?, Hydaticae, 

 &c., and insects ; but of these latter forms we have none yet 

 recorded from Yorkshire. 



Terrestrial life is abundantly marked, but only by plants. Of 

 these we have a large catalogue, including the following groups, 

 among which Ferns, Lepidodendra, and Sigillarise are predomi- 

 nant. 



Asterophyllites. F. Pecopteris. 

 F. Alethopteris. Pinites. 



Calamites. Sagenaria. 



F. Cyclopteris. Sigillaria. 



Halonia. F. Sphenopteris. 



Lepidodendron. Ulodendron. 



F. Neuropteris. 



Of fruits the most remarkable are Trigonocarpon and Cardio- 

 carpon. The prefix F. marks genera of Ferns. 



PAL./EONISCIAN PERIOD. Thus toward the close of the 

 Palaeozoic creations, we have in this region unequivocal dis- 

 closure of broad surfaces of the old sea-bed in a state fitted for 

 abundant vegetation ; this is followed by an epoch of great and 

 extensive disturbance, resulting in the production of a mass of 

 land, on the east of which is a very extensive sea. And again, 

 we perceive the singular effect of watery violence, extensive 

 wearing and partial levelling of the surface of the uplifted coal- 

 measures and older strata before the next class of deposits was 

 produced. This fact is evident in the range of country north- 

 ward from Aberford, as far as the Tees ; but, from the unequal 

 hardness of the materials, the surface is far less uniform than in 

 the admirable example of the Palaeozoic series. In this sea new 



N 



