AGE OF MOLLUSKS. 



199 



Fig. 109. 



chief representatives of the division of Articulates called 

 Crustaceans in the age of Mollusks. Some of the species 

 of this extensive family are shown in Fig. 110. These 



1. Phacops. 2. Trinucleus. 3. Ampyx. 4. Ogygia, 5. Ilamus. 6. Calymene. 

 7. Calymene coiled up. 



Fig. 110. 



animals, as you see, are divided lengthwise into three 

 lobes, and hence comes their name. They have, trans- 

 verse to these, the common ring-like divisions of the Ar- 

 ticulates. Their eyes, which were quite prominent, were 

 compound. They had the power of curling themselves 

 up like the wood-louse, as exhibited in Fig. Ill (p. 200). 



