INVEKTEBRATE ANIMALS. 7 



Class ACTINOZOA. axxjv, a ray; ^Soov, an 



animal. Internal cavity compound. 



The groups in this class are named and arranged chiefly after Milne 

 Edwards' Histoire Naturelle des Coralliaires ; but most valuable 

 aid hat been received from the magnificent work by James Dana, 

 on the Zoophytes of the United States Exploring Expedition, 

 1838-1842, 



Group 17. — Order RUGOSA. rugosus, wrinkled. 



The members of this order are, with rare exceptions, 

 only known as Palaeozoic fossils. The rays 

 are in multiples of four. 

 ^ Polished sections, chiefly from Devonian rocks. 

 The Order Rugosa includes 224 species. 



Order ZOANTHARIA. ?wov, an anhyial; «v9oj, 



a floicer. Parts in multiples of 5 or 6. 

 Sub-order SCLERODERMATA. (DcAvjpo?, hard; 

 Upixa, the skin. Corallum secreted within the 

 animal. 

 Division TABULATA. Corallite divided by horizontal 

 plates : rays not developed. 



Group 18. — Genera SERIATOPORA (Lamarck), and 

 POCILLOPORA (Blainville). The former from 

 series, a row ; the latter from pocilluin, a little cup. 

 Estimated number of species : recent, 28 ; British, ; 

 fossil, 14 ; Palaeozoic. 



^ Corals from the Pacific and Indian Oceans, in- 

 cluding a very beautiful Sei'iatopora possibly 

 undescribed : other examples from the Red 

 Sea, &c. 

 Group 19.— Family FAVOSITID^. Favus, a honeycomb. 

 Estimated number of species, 102 ; all Palaeozoic fossils. 

 IT The Chained-Coral and other species from the 

 Wenlock Limestone, &c. 



