4 HALKYARD, Fossil Foraminifera of the Blue Marl 



and consisted of much quartz sand, grains of glauconite, 

 Foraminifera, Polyzoa, Ostracoda (very rare), Echinoderm 

 remains, Sponge-spicules, fragments of Molluscan shells and 

 sand-casts of the same. Casts of Foraminifera occur in pyrites, 

 •calcite, and glauconite. 



Sample No. p. — I lb. of sandy marl from base of Cliff about 

 150 yards south of TErmitage. Residue (which was fine) 

 after washing weighed 420 grains, and consisted of sand, 

 Foraminifera, Ostracoda, spines and fragments of tests of 

 Echinus, fragments of Molluscan shells, with very rarely 

 Crustacean remains, plates of Synapta, and a few spicules of 

 Alcyonidas or Gorgonidse. 



The residues spoken of above were such as would pass 

 through a sieve of twenty meshes to the inch. 



From the above analysis it will be seen that generally 

 speaking the Blue Marl is of similar character throughout a 

 large portion of its great thickness, though it does vary slightly 

 in different parts; thus Sample No. 1 was very light-coloured 

 and was easily seen to contain iron oxide in appreciable quan- 

 tity. Sample No. 6 was notable for its micaceous constituent, 

 while in Sample No. 8 glauconite was conspicuous. 



The gatherings taken in April, 1897, were chiefly from 

 the marl beds in the neighbourhood of the end of the sea-wall, 

 between tide-marks, and particular attention was paid to the 

 search for sandy "pockets/' which were found to be very rich 

 in the larger forms. One "pocket" of a few inches square anc^ 

 -an inch or so in depth was found to contain over fifty specimens 

 of Orbitoides tenuicostata, Gumbel, besides numerous other 

 species. At the same time search was made for large conspicu- 

 ous isolated specimens, and many fine Nodosaricz were 

 obtained. Those of 1902 were partly from the end of the sea- 

 wall and partly from top of Cliff 100 yards S. of l'Ermitage. 



As regards the fact noted that in Sample No. 5, 1893, the 

 porcellanous species were mostly represented by casts, it will 

 be as well to refer here to the experiments made by 

 Cornish & Kendall* as to the relative stability, or resistance 

 to solubility in presence of carbonated water, of porcellanous 

 and vitreous Foraminifera, the former presumably being com- 

 posed of carbonate of lime in the form of aragonite and the 

 latter of the same substance in the form of calcite. The authors 

 show that the stability of aragonite is much inferior to that of 



*On the Mineralogical Constitution of Calcareous Organisms, Geol. Mag., 

 Dec. III., Vol. V., No. 2., 1888, pp. 66—73. 



