154 



THREE CRUISES OF THE " BLAKE. 



bean. 



The specimens of Fungia symmetrica, and Diaseris 

 crispa (Fig. 477), if found in a sea where 

 larger Fungise were common, would natu- 

 rally be considered as the young of one of 

 them. 



Alitalia explanata (Fig. 478) is the 

 first species of this tertiary genus found 



Fig. 478. — Antillia ex- 

 planata. |. (Pourtales. ) 



living. 



Attached to the test of an Asthenosoma, 

 from a depth of 373 fathoms near Montser- 

 rat, came up a fine specimen of the delicate Leptonemus dis- 

 cus (Fig. 479), in which the corallum is reduced to a mere lace- 

 work. 



> 



j M 



f& 





/y. 



gv 





m 



Fig - . 479. — Leptonemus discus. | . (Challenger.) 



Among corals recalling extinct types are specially to be men- 

 tioned Haplophyllia (Fig. 480), Duncania, and 

 Guynia, which were surmised by Pourtales to be- 

 long to the Rugosa, an order established by Milne- 

 Edwards and Haime for a large number of fossil 

 corals, abundant in palaeozoic times. Their chief 

 characteristic is the development of the septa from 

 four primary ones (Fig. 481), whilst in all of the 

 living corals the primary number is six. In addi- 

 tion, the chambers are closed by floors. Ludwig 

 lias shown, however, that this tetrameral arrangement of the 



Fig. 480. 

 Haplophyllia 

 paradoxa. 1; 

 (Pourtales.) 



