199 



less extent, to which marine life may have had access at a period long 

 past, notwithstanding the present want of geological proof on the 

 spot by which such an idea can be substantiated, the following quota- 

 tions from the most eminent writers upon limestone formations and 

 upon the structure of caves in other parts of the world, will show 

 that the suggestion is within the limits of the probable. 



Professor DANA, in his " Corals and Coral Islands," p. 360, writes 

 as follows : " The elevated coral limestone, although in general a hard 

 and compact rock, abounds in caverns. They may be due in part to 

 open spaces, or regions of loose texture, in or between the strata. 

 But in most cases they are a result of solution and erosion by the 

 fresh waters of the land, or the waves and currents of the ocean, subse- 

 quent to the elevation. On the island of Mesia, many caverns open 

 outward in the coral limestone cliff* and in some were large stalac- 

 tites." 



In the very important work on caves by Mr. DAWKINS, recently pub- 

 lished under the title of "Cave Hunting," the learned author, under 

 the heading of "The Various Ages of Caves," states "It is very prob- 

 able that caves were formed in calcareous rocks from the time that they 

 were raised to the level of the sea, since they abound in Coral Islands." 

 After quoting some facts from Dana's work, he goes on to say : 



" Calcareous rocks might therefore be expected to contain fissures 

 and caves of various ages. In the Mendip Hills they have been proved 

 by Mr. Charles Moore to contain fossils of Rhsetic age, the character- 

 istic dog-fishes Acrodus minimus and Hybodus reticulatus, the elegant 

 sculptured Ganoid fish, Qryrolepis tenuistriatus and the tiny marsupials, 

 Microlestes and its allies. This singular association of terrestrial with 

 marine creatures is due to the fact, that while that area was being 

 slowly depressed beneath the Rhsetic and Liassic seas, the remains 

 were mingled together on the coast line, and washed into the crev- 

 ices and holes in the rock. 



The older caves and fissures have very generally been blocked up 

 by accumulations of calc-spar or other minerals, and they are arranged 

 on a plan altogether independent of the existing systems of drainage. 



It is a singular fact that no fissures or caves should, with the above 

 exception, contain the remains of animals of a date before the Pleis- 

 tocene age. There can be but little doubt that they were used as 

 places of shelter in all ages, and they must have entombed the re- 

 mains of the animals that fell into them, or were swept into them by 

 the streams. Caves there must have been long before, and the Eocene, 

 Palaeotheres and Anoplotheres met their death in the open pitfalls, 



* On p. 194 this cliff is described as " a white and solid limestone, seldom pre- 

 senting any traces of its coral origin." , 



