DEVONIAN AGE. 



259 



of an inch in diameter, marked with eight spiral ridges, which he regards as seeds of a 

 Chara. These frequently occur also in the cellular chert at the Falls of the Ohio. 



2. Animals. 

 The Corniferous period was, as has been stated, eminently the coral- 

 reef period of Paleozoic time. 



1. Invertebrates. — The existence of Sponges is indicated by the 



Figs. 485-491. 



487 



Polyps. — Fig. 485, Zaphrentis gigantea ; 486, Z. Rafinesquii ; 487, Phillipsastrea Verneuili ; 

 488 a, C}athoph3'llum rugosum; 489, Favosites Goldfussi ; 490, Syringopora Maclurii ; 491, 

 Aulopora cornuta. 



presence of their siliceous spicula in the hornstone, two slender forms 

 of which are shown in Figs. 484 A,j, k, page 257, and others in I, m, n. 



Figures 485 to 491 represent some of the corals ; 

 486 shows well the radiated cup-shaped termination 

 to which the name Cyathophylloid corals (from Kva- 

 6os, cup, and <£vA/W, leaf) refers ; 485 has both 

 extremities broken off, but exhibits the interior radia- 

 tion ; 489 is a portion of a common species of Favo- 

 sites (honey-comb coral, named from favus, honey- 

 comb), a kind that sometimes occurs in hemispheres 

 five feet in diameter ; 487 is part of the surface of 

 a common massive coral. 



Among Echinoderms, the most interesting are species of the group 

 of Blastids, or Bud-Crinoids, having no proper arms, one of which is 



Nucleocrinus Ver- 

 neuili. 



