242 MR. C. T. TRECHMAXNT OX THE LITHOLOGT [June 1914, 



Lower Shell-Limestones. 



Claxheugh Quarry. — XLI. Crinoid- stems freed from their 

 matrix. A section of the crinoidal rock shows it to be full of 

 remains of organisms which are almost completely dolomitized, and 

 have a ciyptocrystalline structure. The matrix consists of closely- 

 packed allotriomorphic dolomite-grains full of inclusions. Staining 

 takes place locally, showing, the presence of a very small quantity 

 of calcite ; but no well-defined grains are seen. Brown patches of 

 impurities occur. (See PI. XXXVI, fig. 2.) 



Ford Quarry, Claxheugh. — A development of cellular rock 

 occurs here on the flank of the reef, very closely associated Avith 

 Shell-Limestone. 



XL1I. Very fine, incoherent, crystalline powder filling the 

 angular cavities. 



XLIII. The hard cellular matrix enclosing the above powder. 



XLI. XLII. XLIII. 



Insoluble residue 3*65 l 2-41 2*04 



Fe.,0 3 , etc 0*32 0*65 0-45 



CaC0 3 52-26 54*21 93*35 



MgC0 3 43-81 43-53 5-08 



Totals 100-04 100-80 100-92 



Calcite 0'10 2-39 87*31 



Dolomite 95*97 95*35 11-12 



Black hall Colliery Sinking. — Towards the base of the 

 Shell-Limestone. 



XL1V. This is an extremely-fossiliferous whitish rock, with 

 a fully - developed reef -fa una. including Spirifer alatiis. The 

 shells are represented by a loose white powder. 



XLV. Highly-fossiliferous yellowish rock, completely built up 

 of specimens of Caviar oplioria global iua, Pecten pusillus, and 

 other forms. 



XL VI. Shell-substance of a Prodactus liorridus. White, rather 

 powdery material, retaining in part the original shell- structure. 



XLVII. Shell-substance of an Area turn Ida. White, very 

 incoherent powder, partly preserving the shell-structure. 



XLVIII. The mould filling the interior of XLVI. It was half 

 filled with a compact, pale-yellow rock, enclosing remains of 

 ostracods and other small forms. 



XLIV. XLV. XLVI. XLVII. XLVIII. 



Insoluble residue ... 0*45 1*71 O'll 0-28 1-45 



Fe 2 3 , etc 0-30 0-47 0-28 0-56 0-67 



CaC0 3 55-44 55*69 56-02 53-87 54-41 



MgC0 3 43-94 42-98 43-77 45-05 43-17 



S0 3 ..' 0-14 0-14 tr. tr. tr. 



Totals 100-27 100*99 100*18 99*76 99-70 



Calcite 3*13 4*52 3*91 0*24 3*01 



Dolomite 96*25 94*15 95*88 98*68 94*57 



1 



One of the crinoid ossicles was partly silicified. 



