ANNOTATIONS AND ADDITIONS. 275 



nature who has added to his own many and valuable observations a 

 comparison with those of others in all parts of the globe, Charles 

 Darwin, places with greater certainty the depth of the region of 

 living corals at 20 to 30 fathoms. (Darwin, Journal, 1845, p. 467 j 

 and the same writer's Structure of Coral Reefs, pp. 84-87 j and Sir 

 Robert Schomburgk, Hist, of Barbadoes, 1848, p. 636.) This is 

 also the depth at which Professor Edward Forbes found the greatest 

 number of corals in the Egean Sea : it is his " fourth region" of 

 marine animals, in his very ingenious memoir on the " Provinces of 

 Depth/' and the geographical distribution of Mollusca, at vertical 

 distances from the surface. (Report on JEgean Invertebrata, in the 

 Report of the 13th Meeting of the British Association, held at Cork 

 in 1843, pp. 151 and 161.) The depths at which corals 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 Forbes 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, Voyage 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- 

 laria grsenlandica, living, from depths of 236 fathoms. (Ehrenberg, 

 in the Abhandl. der Berl. 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, vol. 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 



