26 FOUNDERS OF OCEANOGRAPHY 



fresh, brackish, and salt-water conditions over this part of 

 England when the Purbeck group was in course of deposition. 

 Our naturalist made the further important discovery that 

 on several separate horizons these strata enclose the shells 

 of some genera of still existing air-breathing moUusks — 

 creatures which had not till then been found in so ancient a 

 formation. It was characteristic alike of his humour and of 

 his habit of making fun of his scientific brethren, and even 

 of himself, that in some verses on what he called ' Negative 

 Facts,' given at the Red Lion Dinner at Ipswich, and 

 published in the Literary Gazette for 12th July, 1851, he 

 instanced the finding of these shells as upsetting a premature 

 conclusion : 



Down among the Purbecks deep enough, 



A Physa and Planorbis 

 Were grubbed last year out of freshwater stuff, 



By Bristow and E. Forbes. 

 (Agassiz just had given his bail 



'Twas adverse to creation 

 That there should live pvdmoniferous snail 



Before the Chalk formation.) 



*' The discovery, however, carried with it a wider signi- 

 ficance. The occurrence of these snails suggested to Forbes 

 that if air-breathing mollusks existed in Purbeck time, 

 remains of mammalian life might hopefully be searched for 

 in the same stratum as that which contained the shells. His 

 sagacious prognostication was fulfilled not long after, when 

 bones of reptiles and insectivorous mammals were exhumed 

 where he had indicated." 



The second example of Forbes's geological work which 

 I have selected for mention is his celebrated paper, " On the 

 Connexion between the Distribution of the Existing Fauna 

 and Flora of the British Isles and the Geological Changes 

 which have affected their Area," published in 1846, in Vol. I. 

 of the Memoirs of the Geological Survey, and universally 

 regarded as a classic on the subject. 



Forbes recognized that the origin of the fauna and flora 



