112 Lieut. Nelson on the Geology of the Bermudas. 



stone containing it. It seemed difficult at first to account for these large 

 shells {Turbo Pica) being found on heigh ts^ where, from their weight, it was 

 impossible to suppose they had been carried by the wind ; but a solution 

 may be found in the habits of the Soldier Crab, which, on more than one 

 occasion, I have seen running about in these shells. 



The most interesting organics with which I have met, were in the rock now inclosed by the 

 North Bastion, at Ireland Island. 



Whilst cutting the escarp of this work, a large block of reef was discovered in the solid rock, 

 fifteen or twenty feet from the surface, and at about four feet above high water. This specimen 

 contained Mceandrina areolata, the common Mytilus of the coast, retaining its black colour, and 

 a pink Millepore very common in the serpuline reefs. This spot, conceiving the truncated strata 

 of Ireland to be restored to their proper form, must have been at the very apex of the saddle, 

 and is perfectly distinct from the loose, soft, and newer sandstones. Above the level of this 

 spot, lie the strata a a, fig. 8, which for some hundred yards along the north side, consist chiefly 

 of a hard subcrystalline limestone. 



Although this stone is by no means as subcrystalline as the transition, or other old limestones, 

 yet it is sufficiently so to show that the structure can be attained by very new rocks, and by otiier 

 means than that of heat under pressure. Had heat been in anywise applied to such extent, it is 

 more than probable much of the carbonaceous* matter (one of the constituents of the shelly sand) 

 would have been altogether evolved, and would not have remained, black and mixed amongst 

 the particles of the rock. At all events the colours of the Mytilus and Millepora could not 

 possibly have been retained. 



In the centre of this rock, fig. 8, was a cavern ; and entangled amongst tlie stalagmitic lining 

 (as well as in that of other caves and crevices), or else lying in heaps in the loose red earth within, 

 we found abundance of a large and delicate Helix. In another instance, upwards of thirty 

 bushels were discovered, without any earth among them : a circumstance easily accounted for by 

 the common habit of these animals to shelter in holes, wherever they can find them. 



* I have paid some attention to the membranous tissues of zoophytes, and find full proof of 

 their existence in many varieties of the Bermuda stone. A careful solution in very dilute mu- 

 riatic acid, generally gives a minute flocculent precipitate, which the microscope shows to be the 

 mere animal part of the subject. 



