Walker — Greensand Brachiopoda, 399 



begins to decompose, giving out light and overcoming chemical 

 affinity. 



We have endeavoured to show in these few notes how intimately 

 the physical forces are connected, if they be not indeed all modifi- 

 cations of one force. 



If the proper comprehension of the phenomena of nature involves 

 a knowledge of physics and chemistry, how necessary must the 

 study of these sciences be to every geological student who diligently 

 seeks to understand the " Testimony of the Rocks." 



Every effect produced, however vast, or however limited in extent, 

 is but the exhibition of the direct action of some physical force, 

 inducing also in very many cases chemical change. 



The sun's heat converting water into vapour; the winds con- 

 veying the rain-cloud from one region to another; the tides and 

 currents of the ocean ; the degrading and transporting action of 

 ice and snow, rain and rivers, upon land-surfaces ; the re-elevation of 

 the ocean-bed by subterranean force ; the deposition from solution 

 or otherwise, of mineral matter in a crystalline form in lodes and 

 veins ; the segregation of mineral -matter (originally diffused through 

 strata) into layers, nodules and concretions ; the phenomena of vol- 

 canoes and thermal springs ; these and ten thousand like illustrations 

 might be offered of the effects of physical force (with or without 

 chemical action), operating around us continually. 



III. — On the Species of Brachiopoda, which occue in the Lower 

 Greensand at Upware. 



By J. F. Walker, B.A., F.G.S., etc. 



(PLATES XVIII. and XIX.) 



HAVE in previous papers given some account of the remark- 



I 



able Lower Greensand deposit at Upware,^ and have also de- 

 scribed three new species of TerebratididcB^ from this locality. 

 Having obtained additional specimens of the rarer forms, and several 

 new species, and having received many valuable suggestions from 

 Mr. Davidson and Mr. Meyer, I propose in the present paper, first 

 to describe some of the new species, then to make a few remarks on 

 the numerous species of Brachiopoda which occur in this deposit, and 

 finally to indicate their distribution in the Lower Greensand deposits 

 of this country. 



In the field which is at present worked at Upware, there are found 

 very few of the remarkable sponges, such as VerticiUites anasto- 

 mosans, Manon macropora, etc., which occurred so abundantly in the 

 field which was being worked when I first gave a short account of 

 the bed. The section in May, 1868, was as follows : — 

 Sand 



Coprolitic bed 



Clay 



1 Vide Geol. Mag., 1867, Vol. IV 



2 Vide Geol. Mag., 1867, Vol. IV, 



3|ft. 

 not pierced. 



, p. 309, etc. 



, p. 454, PI. XIX. 



