306 NATURAL SCIENCE [November 



deposit by the action of currents. In obtaining the data from the 

 recent species attention has been especially paid to evidence of depth 

 at which the particular species occurs most frequently, and where it 

 attains its best development. 



The material on which these calculations are based cannot 

 afford a complete comparison on account of the number of Gault 

 forms which are quite unknown in recent deposits, but this not- 

 withstanding, an approximation to the truth may perhaps be 

 obtained. 



The noteworthy and important groups of foraminifera found in 

 the Gault, and which are not exactly represented in our recent 

 faunas are — 



( 1 ) The strongly costate Nodosariae ; 



(2) The complanate and limbate Frondiculariae ; 



(3) The sulcated and limbate A r aginulinae ; 



(4) The remarkably developed and attached Eamulinae, the 

 allied genus Vitriwebbina ; 



(5) And the limbate, reticulate, and spinose Pulvinulinae. 



The comparatively large size and redundant growth of these 

 forms indicates favourable conditions for development, in which a 

 high bottom temperature and a sufficiency of calcareous material 

 dissolved in the water would form important factors. Another 

 possibly important condition was the accumulation of marine shells 

 over which this part of the Benthos of the Gault Sea was able 

 to wander, and amongst which it could shelter. In the case of the 

 Eamulinae and Yitriwebbinae these curious recent organisms 

 attached themselves to the shells of the mollusca. 



Although marked changes are observable in the character of the 

 deposits forming the Gault series in Kent, where they consist of 

 green-sands, clays, and marls, it is somewhat remarkable that the 

 actual rhizopodal fauna does not greatly vary ; and so far as one 

 can judge from the results now before us, the depths were not 

 subject to so much oscillation as the lithological character of the 

 beds might at first sight seem to demand. They are all more or less 

 comparable with deposits forming in the moderately deep seas of the 

 present day : they are probably represented by the green, blue, and 

 red muds and the green-sands for the Lower Gault ; and by the semi- 

 pelagic or terrigeno-ghbigerina ooze (the meeting ground of the 

 terrigenous and the pelagic deposits) for the marls of the Upper Gault. 



In connection with the subject it may be remarked that some 

 years ago Professor T. Kupert Jones stated, in a note on an annelid 

 bed at Westwell Leacon (3) that his colleague, Professor W. Kitchin 

 Parker, believed the Gault Sea to have been 100 fathoms. 



F. G. Hilton Price believes the Gault Sea not to have exceeded 

 100 fathoms in depth, and probably much shallower (4). 



