AlfNITEESAET ADDRESS OF THE PRESIDENT. Ivii 



different arrangement of our seas and continents, destructive of the 

 higher forms of life, and accompanied by the introduction of northern 

 forms of partly corresponding classes. 



Edward Forbes concluded from his researches in. the ^gean that 

 parallels in latitude are equivalent to regions in depth ; and he subse- 

 quently showed this hypothesis to hold good by the occurrence at 

 various depths in southern seas of northern species of moUusca. Hence 

 cold-water species of Testacea can have a much wider range in 

 latitude than warm-water species. MM. D'Archiac and De Ver- 

 neuil had already, on purely palseontological grounds, concluded 

 that those species which were found at many places, and in districts 

 distant one from the other, are almost always those which have lived 

 through many successive formations (systhmes)^ ', or, as it was better 

 expressed by Mr. Eogers, " the species of which the geographical distri- 

 bution is the widest have also the greatest vertical range.'''' Reasoning 

 from these data, M. D'Archiac observed that those geologists who 

 saw " beds of different age everywhere where they found different 

 fossils, were liable to make serious mistakes ; for the same bed taken 

 at two distant points and having a natural difference of level, say 

 of 300 feet, might present very distinct groups of species, and might 

 lead to the erroneous conclusion that these two parts of the same 

 bed were not contemporaneous "f. Edward Forbes also observed 



* BuU. Soc. Geol. de France, vol. siii. p. 260, 1S42. 



f Bull. Soc. G-60I. de France, 2nd ser. vol. ii. p. 484, 1845. As the discussion 

 which ensued on this communication bears on the subject of these deep-sea 

 investigations, I give a few extracts from it, which may be new to some present : — 



" M. de Verneuil ajoute que, sur les cotes de Suede et de Norvege, la ou la 

 mer est assez profonde, M. le Professeur Loven, de Stockholm, a observe parjni 

 les mollusques une distribution verticale correspondant a leur distribution hori- 

 zontale, suivant les latitudes. Ainsi, entre Grothenbourg et la Norv^ge, M. Loven 

 a trouve a 80 toises de profondeur, des especes qui, sur la cote du Finmark, 

 habitent a 20 toises ; plusieurs especes s'elevent meme sur cette derniere cote 

 jusqu'a la region littorale, tandis que dans le sud, elles se tiennent toujours a 

 12 oa 15 toises au-dessous du niveau de la mer." 



" M. filie de Beaumont fait remarquer .... Aujourd'hui la temperature a la 

 surface de la mer a I'equateur est de 27^° [C], tandis qu'au fond elle est de 2°. II 

 n'y a aucune raison de croire a ces differences autrefois." . ..." La tres-grande 

 masse de la mer equatoriale est k une temperature tres-basse et seulement d'un 

 petit nombre de degres au-dessus de zero." 



M. Pouillet also, in his ' Elements de Physique,' vol. i. p. 166, 1847, speaking 

 of deep-sea fishes, observes : " On pent juger par la que les regions delamer ont 

 leurs peuples diife rents, non seulement suivant les climats, mais encore suivant 

 les profondeurs." 



VOL. XXVII. e 



