300 The Levenshuhne Limestones. 



These last limestones (No. 8) are, from a marble mason's 

 point of view, the most valuable of all, being, when polished^ 

 the most beautiful of the series. They have a lovely deep 

 colour, mottled with paler pink spots, and the marble polish 

 is perfect. The Spirorbis with which we started is here in 

 abundance. A thin section under the microscope shows 

 the red markings to be hematite stains, mottled further 

 with hosts of Spirorbis. There are many shells of Entomo- 

 straca and fragments of shells, and long curved tubular 

 objects, probably Serpulites Carbonarius. The veining is 

 most noticeable under the microscope ; it runs across the 

 subject like rivers filled in with clear crystals of calc spar, 

 as if the whole limestone were brecciated, the intervening 

 spaces having been filled in by subsequent crystallization. 



