74 PHYSIOGNOMY OF PLANTS. 



live would seem, however, to be very different in different 

 species, and especially in the more delicate ones which do 

 not form such large masses. 



Sir James Ross, in his Antarctic Expedition, brought 

 up corals with the sounding lead from great depths, and 

 entrusted them to Mr. Stokes and Professor Eorbes for 

 more thorough examination. On the west of Victoria 

 Land, near Coulman Island, in S. lat. 72 31', at a depth 

 of 270 fathoms, Retepora cellulosa, a species of Hornera, 

 and Prymnoa Rossii, were found quite fresh and living. 

 Prymnoa Rossii is very analogous to a species found on the 

 coast of Norway. (See Ross, Yoyage of Discovery in the 

 Southern and Antarctic Regions, vol. i. pp. 334 and 337.) 

 In a similar manner in the high northern regions the whalers 

 have brought up Umbel! aria grsenlandica, living, from depths 

 of 236 fathoms. (Ehrenberg, in the Abhandl. der Berk 

 Akad. aus dem J. 1832, S. 430.) We find similar relations 

 of species and situation among sponges, which, indeed, are 

 now considered to belong rather to plants than to zoophytes. 

 On the coasts of Asia Minor the common sponge is 

 found by those engaged in the fishery at depths varying 

 from 5 to 30 fathoms; whereas a very small species of 

 the same genus is not found at a less depth than 180 

 fathoms. (Forbes and Spratt, Travels in Lycia, 1847, 

 Yol. ii. p. 124.) It is difficult to divine the reason which 

 prevents Madrepores, Meandrina, Astrsea, and the entire 

 group of tropical Phyto-corals which raise large cellular 

 calcareous structures, from living in strata of water at a 

 considerable depth below the surface of the sea. The dimi- 

 nution of temperature in descending takes place but slowly ; 



