8 M. SANDER RANG 



tion to the proofs derived from the condition and preservation 

 of the bones found in, and immediately under, this calcareous 

 tegument, which compel us to conclude that its formation 

 dates from the time immediately subsequent to the introduc- 

 tion of the soil ; and that it owes its origin to the extraordi- 

 nary condition into which the surface of our globe passed, as 

 a consequence of the equally extraordinary catastrophe that 

 occasioned the destruction of the whole race of animals pre- 

 viously existing, and the introduction of their remains into 

 the caves. This stalagmitic crust, which, with so few ex- 

 ceptions, covers the surface of the soil in all the Brazilian 

 caverns, is never found beneath it ; which circumstance con- 

 trasts so strongly with the abundance of the stalagmitic blocks 

 produced during the remote period that preceded the intro- 

 duction of the soil, as to be sufficient, in connection with the 

 adduced proofs, to confirm their distinct origin. 



I fear that I must have wearied the Society by dwelling so 

 long on this point; I trust however that its practical impor- 

 tance will plead my excuse. Future visitors to these caverns 

 may perhaps find here a hint to guide them in their search 

 after the treasures contained in them, and in the determina- 

 tion of the age of those treasures. The same remark will 

 hold good with respect to the observations I shall next pro- 

 ceed to offer on the conditions under which the bones are 

 foimd in the caverns. 



(To he continued). 



Art. II. — On the Genus Argonauta. By M. Rang. 



( Continued from Vol, iW. page 532.^ 



Thus the intention of the membraniferous arms with which 

 certain species of poulps are provided is now known. These 

 organs envelope the argonaut-shell as the lobes of the mantle 

 in some other kinds oimollusca envelope their shells. But for 

 what purpose are they so disposed ? Some naturalists have 

 thought, and there are those among the number whose learn- 

 ing and talent are incontestible, that the poulp secreted the 

 shell by means of its airholes ; would then an opinion be 

 more unreasonable which should attribute this secretion to 

 the membranes themselves ? The slender form, the fragile 



