277 



are by no means equally diffused. In the brown clouded 

 marbles of Beetham Fell, they are so very plentiful as to 

 crowd the field of the microscope. Similar characters 

 belong to the white Mountain Limestones of Russia.* 



Amongst these fossils I distinguish a beautiful concamer- 

 ated shell, most probably a Foraminifer, with a large opening 

 in each septum, on the interior edge. Formerly I saw in 

 the possession of Mr. John E. Bowman a specimen of this 

 kind, visible to the naked eye, and named it Endothyra 

 Bowmanni. ( See Fig. \,) The volutions are swollen 

 externally between the septa. 



Another common form of Foraminifera is represented in 

 section in Fig, 2. 



Beside these, are many minute spiral shells of Gasteropoda. 



In the Magnesian Limestone, as yet, I have been com- 

 paratively unsuccessful. The compact parts of the rock 

 seem to consist of earthy grains, imbedded in a cement of 

 crystalline carbonate of lime ; and this is a very general 

 character of the so-called earthy limestones. Similar 

 characters belong to the Magnesian (Permian) Limestone 

 of Russia. 



The Nodular Lias beds of Yorkshire I have not yet 

 examined. The blue Lias of the South of England is in 

 some beds rich in portions of Crinoidea, but in others 

 almost devoid of organization. Small Conchifera appear 

 in the sections, but I have not observed Foraminifera. 

 There are in this stone some singular patches, (green, by 

 transmitted light,) which I am as yet unable to resolve. 



The whole Lias of the vicinity of Bath is a mass of minute 

 granulation, cemented by a carbonate of lime. There are 

 many little concentric textures, with a dark centre. 



* I am indebted to Sir R. I. Murchison for specimens of the Palaeozoic 

 Limestones of Russia. They have furnished many interesting facts under the 

 microscope. 



