THE GEOLOGY OF BERMUDA. 31 



FOSSILS. 



Fossils of recognizable character are found chiefly in the compara- 

 tive ely scanty deposits of beach-rock. The drift-rock, however, contains 

 in abundance shells of several species of land snails, the most common 

 being Zoniies hermudensis and the perhaps specifically distinct variety 

 nelsonii, Helix microdonta, and Helix circumfirmaia. Among these it is 

 noteworthy that Zonites hermudensis v^ar. nelsonii no longer exists in a 

 living state. The other three forms are still abundant residents of the 

 islands. Shells of Livona pica are also abundant in the drift-rock, hav- 

 ing doubtless been carried up from the water by "soldier" or hermit 

 crabs. I have also observed bones of birds and fragments of the shells 

 of crabs. The remains of marine shells and corals in the drift-rock are 

 usually so finely comminuted as to be unrecognizable. 



The beach-rock in several localities contains marine shells in great 

 abundance and variety. Nelson appears to be not far out of the way in 

 the statement that "almost ev^ery shell now known in the surrounding 

 sea may be found in the rock."* I made no endeavor to make a com- 

 plete collection of the fossils of the beach-rock. I append, however, 

 ii list of the shells which have been recognized among the specimens of 

 rock which I collected to illustrate the geology of the islands. The list 

 may be of some interest as indicating in general the most common spe- 

 cies of fossils : 



Mytilus extistus, Linn., 



Pectunculus , 



Barbatia domingensisy Lam., 



Lucina pennsylvanica^ Linn., 



Chama maceropJiylla, Chem., 



Chama lingtui-felis, Keeve, 



Bulla media^ Linn., 



Fissurellu barbadensis, Gmel., 



Fissurella graeca^ Lam., 



Livona pica, Linn., 



Iferita pehronta, Linn., 



Trtmcatella , 



Yermetus Inmbricalis, Linn., 



Tectarins muricatus, Linn., 



Gerithium versicolor, C. B. Ad., 



Cyplioma gibbosa, Linn., 



* Op. cit., p. 114. 



