MARINE BIOLOGICAL STATION AT PORT ERIN. 69 
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 
*T was adverse to creation 
That there should live pulmoniferous snail 
Before the Chalk formation.) 
The discovery, however, carried with it a wider significance. 
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’ 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 recognised that the origin of the fauna and flora 
of a country could not be solved from biological studies alone, 
but would require in addition the evidence supplied by Geology 
in regard to former changes in climate, land and water. 
Dealing with the flora of the British Islands he distinguished 
five sub-floras or assemblages of plants—(1) a limited 
* Lusitanian’”’ flora in the west and south-west of Ireland, 
comprising saxifrages, heaths, the arbutus, a Pinguicula, and 
E 
