FOSSIL CEPHALOPODS. 309 



the geologist is sure to find numbers of this group 

 present. 



The Devonian limestones cropping up in the 

 neighbourhood of Torquay and Newton Abbot, and 

 also the Upper Devonian rocks at Petherwin, in 

 Cornwall, have yielded about sixty species of fossil 

 Cephalopoda. At Petherwin the chief kind is the 



Fig. 307. Section of Liassic Ammonite, showing chambers filled with spar. 



beautiful Clymenia, of which eleven species are there 

 met with. Goniatites is another genus not uncommon 

 at Petherwin, although not so numerously represented, 

 as far as species go, as Torquay. The richly coloured 

 red and yellow limestones at the latter place are cut 

 and polished, and then present a very lovely appear- 



