32 



ORGANIC REMAINSDEVONIAN SYSTEM. 



Cyatho'phyUwn (fig. 18), (from the Greek, kitathos, a cup, and 

 pi mil on, a flower). The abundance of corals of this genus in the 

 Silurian system proves that the seas of that epoch must have 

 teemed with these zo'ophytes. The Cate'nipora (fig. 19), (from 



the Latin, catena, a 

 chain, and poms, a 

 pore). The oval form 

 of the cells when united 

 laterally, and the flexu- 

 ous disposition of the 

 lamellae, give rise in 

 transverse sections to 

 elegant catenated mark- 

 ings, from which ap- 

 pearance the fossil has 

 received the name of 

 chain-coral. The spe- 

 cies figured (fig. 19), 

 is common in Silurian 

 limestone, and some- 

 times forms hemispher- 

 ical masses more than a 

 foot in diameter. 



36. The organic re- 

 mains of the Cambrian 

 system differ from those 

 of the Silurian system 

 in being less developed ; 

 the genera and species 

 of mollusks and corals 

 found in both are alike. 



37. The DEVONIAN 

 SYSTEM (so called be- 

 cause it is largely deve- 



Fig. 20.* Fossil Fishes of the Devonian System, loped in Devonshire, 



England) forms the su- 

 perior part of the preceding formation. It appears to be composed 



* Explanation of Fig. 20. 1. Pterichthys cornutus, seen from above 

 'Pterichthys, from the Greek, pleron, wing, and ichthos, fi^h : cornutus, La- 

 tin, horned. The horned wing fish). 2. Coccostcus oblongus. These 

 figures are restored with great, accuracy from the best pieservtd specimens 

 hitherto discovered. The British species of fossil wing-fishes, of which 

 five or six are known, are all very small, varying in length from one to 

 eight or ten inches. But in the Devonian strata of Russia enormous spe. 

 cies occur , the spines of some of them exceed a foot in length. See Man- 

 tell's Medals of Creation. London, 1844. 



36. How do the fossils found in the Cambrian rocks differ from those of 

 the Silurian System '/ 



