64 EXCURSIONS IN MADEIRA 



nounced the nodules containing the galeolaria, to have been 

 amygdaloidal, the remains of this tubicola having at first sight all 

 the appearance of an earth, subsequently deposited in the pores 

 of the basalt. Very small balani also adhered to these nodules. 

 I met with two species of trochus on the same shore, and the turbo 

 edulis, which adheres to the rocks, and is generally eaten by the 

 natives : two species of helix ^ lay upon the rocks out of reach of 

 the sea ; the animals had left the shells, which had probably been 

 rolled down from the top of the cliff. In a recess upwards of 150 

 feet from the sea, and nearly as high above its level, I was sur- 

 prised to find rows of stalactites of muriate of soda, frequently a 

 foot long, pendant from the red tufa like so many icicles, and 

 terminating in nodules of the same salt, as large as the half of a 

 duck's egg. Breaking off some of the masses, the salt appeared to 

 be spread over the interior surface, as if the tvifa was impregnated 

 with it; nor is this improbable, when we recollect, that M. Brieslak'' 

 has seen muriate of soda efflorescing from volcanic tufas, in situa- 

 tions very distant from the sea, and that it abounds in such quan- 

 tities in the crater, and in the lava streams of Vesuvius, according 

 to M. Menard de la Groye', that the peasants load themselves with 

 it for their domestic purposes''. The yellow tufa close to the sea, 

 was merely sprinkled with saline particles, like a fine powder, 

 evidently deposited by the spray. 



Sailing from Funchal along the eastern coast to the Brazen 

 Head, we first find the basalt (frequently rudely columnar above, 

 and bellying out like the sails of a ship) above the tufa and scoriae. 



s They both belong to the sub-genus helicella {Gr. aplostomce) of De Ferrussac, 

 but I suspect they are new species. 



'' Introduction a la Geologic, p. 426. 



' D'Aubuisson, Traite de Geognosie, t. 2, p. 595. 



^ Baron de Humboldt found salt disseminated in a clay formation in the Cordilheres, 

 nearly 13,000 feet above the sea. ' Relation Historique, 1. 2, c. 5. 



