310 Ruyal Institution. 



ROYAL INSTITUTION. 



Feb. 23. — At this evening's meeting Prof. E. Forbes gave a lecture 

 " On the light thrown on Geology by Submarine Researches*." Ha- 

 ving alluded to the researches of two Italian naturalists, Donati and 

 Soldani, who dredged the Adriatic about the middle of the last cen- 

 tury, Prof Forbes entered on the important inferences which he had 

 derived from similar investigations in the Irish Channel and in the 

 Archipelago. His first conclusion was, that marine animals and 

 plants are grouped, according to their species, at particular depths 

 in the sea, each species having a range of depth aiipropriated to it- 

 self. Prof. Forbes illustrated this assertion by a diagram, indicating 

 the plants and animals respectively inhabiting what he termed the 

 littoral zone, which extends immediately from the coast — the lami- 

 narian zone, where the broad-leaved fuci are most abundant — the 

 coralline, in which there is an assemblage of mollusca, especially bi- 

 valves and corals, and the deep sea coral, so called because in it only 

 we find examples of large corals on the British shores. Prof. Forbes 

 next alluded to the fact of the number of species diminishing accord- 

 ing to depth, so that by gaining an accurate knowledge of the fauna 

 and flora appropriated to various sea-bottoms, the naturalist can 

 infer their depth : no plants are found below 100 fathoms, and the 

 prol)able zero of animal life is at 300 fatlioms. Sedimentary deposits 

 below this depth are consequently destitute of organic matter. This 

 circumstance bids the geologist to be cautious in inferring that any 

 stratum was formed before the creation of animals, on no other ac- 

 count than that it is devoid of organic remains : he should rather 

 conclude from such deficiency, that the stratum was deposited in 

 very deep water. 



Prof. Forbes next remarked that British species are found through- 

 out the zones of depth in the Mediterranean Sea ; but that in that 

 sea, the proportion of northern testacea in the lower zones greatly 

 exceeds that in the upper, so that there is a representation of cli- 

 mates, or parallels of latitude, in depth. The fourth proposition ad- 

 vanced by the Professor was, that all varieties of sea-bottom are not 

 equally capable of maintaining animal life. The sandy parts are 

 usually the desert ones. Hence the scarcity of fossils in sandstone : 

 though traces of worms (which inhabit the sand) are found in ancient 

 sandstones. As each animal is not able to live, except on its own 

 locality, those marine animals, as the scallop, which are gregarious, 

 deteriorating the ground when they increase beyond a certain ex- 

 tent, die ; then the place becomes silted up, the ground changes, 

 and another race occupies it. This fact explains the phaenomena of 

 distribution of organic remains in rocks ; i. e. their being grouped 

 together in separate strata, fossiliferous strata alternating with those 

 which are free from organic remains. 



* We would refer the reader to the paper which Mr. Forbes published in 

 our 4th volume " On a Shell Hunk in tlie Irish Sea, considered Zoologically 

 and Geologically," and it will be seen how ably and snccessfuUy he has 

 during his voyage followed out the line of inquiry which he suggested four 

 years ago. — See also vol. ix. p. 212. — Ei>. 



