PHYSrCAL HISTORY AND GEOLOGY. 35 



volumes of spray which we should have believed impossible, 

 Were it not for the absolute reliability of the residents of the 

 house who volunteered the information. 



At several points more particularly along the north shore I 

 found marine shells (Lucina, Tellina, etc.) imbedded in unques- 

 tionable drift-rock, and, indeed, it could hardly have been ex- 

 pected that such association should not occur. On the whole, 

 however, these remains were not as abundant as one might 

 have expected to find them. The same is also true in a 

 measure of the occurrence of land-snails. One of the com- 

 monest shells of the lower drift-rock is the large Tv,rho (lAvona) 

 pica, a shell which appears to be very abundant about the coast, 

 but which generally, and perhaps invariably, is cast up with- 

 out the animal. I was unable to find anyone among the local 

 collectors who had seen the animal itself, nor did any member 

 of our party succeed in obtaining an occupied shell. Nelson 

 and Rice both attribute the occurrence of this shell in the 

 drift-rock to transportation by hermit-crabs. I can hardly be- 

 lieve that this is the full explanation. I failed to find any of 

 the shells of the beach inhabited by hermits, and was in this 

 l"espect less fortunate than Nelson, nor do I know of any her- 

 mit of the islands which would be likely to carry about with 

 it the massive full-grown shell. However, my testimony on 

 this point is purely negative. 



I admit with Prof Rice that it is frequently difficult 

 to distinguish between what is assumed to be beach-rock and 

 the regular drift-rock of the islands, especially when the latter 

 occupies a basal and nearly horizontal position. In manj^ 

 places along the south shore where the beach-rock is exposed 

 in heavy beds it occupies but a lirriited horizontal space, being 

 succeeded by highly inclined drift-rock, which descends to the 

 water-level. This succession is unexpected, and might lead 

 one to infer that there have been local differential movements 

 on th'e part of the land. But of course this need not have been, 

 and doubtless was not, the case, since an irregular or indented 

 shore-line Undergoing elevation would form features similar 



