Of GIBRALTAR. 201 



full complement of teeth, the enamel of which was perfed, and 

 its whitenefs and luftre in no degree impaired. In the hollow 

 parts of fome of the large bones was contained a minute cryftal- 

 lization of pure and colourlefs calcareous fpar ; but, in moft, 

 the interior part confifted of a Iparry cruft of a reddilh colour, 

 fcarcely in any degree tranfparent. 



At the northern extremity of the mountain, the concretion 

 is generally found in perpendicular fiflures. The miners there, 

 employed upon the fortifications, in excavating one of thofe M- 

 fures, found, at a great depth from the furface, two fkuUs, which 

 were fuppofed to be human ; but, to me, one of them, if not 

 both, appeared to be too fmall for the human fpecies. The 

 bone of each was perfe(5Hy firm and folid ; from which it is to 

 be prefumed, that they were in a ftate of maturity before they 

 wexe inclofed in the concretion. Had they appertained to very 

 young children, perhaps the bone would have been more porous, 

 and of a lefs firm texture. The probability is, that they belong- 

 ed to a fpecies of monkey, which ftill continues to inhabit, in 

 confiderable numbers, thofe parts of the rock which are to us 

 inacceflible. 



This concretion varies, in its compofition, according to the 

 fituation iir which it is found. At the extremity of Princes 

 Lines, high in the rock which looks towards Spain, it is found 

 to confift only of a reddifh calcareous earth, and the bones of 

 fmall birds cemented thereby. The rock around this fpot is in- 

 habited by a number of hawks, that, in the breeding feafon, 

 neftle here, and rear their young ; the bones in this concretion 

 are probably the remains of the food of thofe birds. At the 

 bafe of the rock, below King's Lines, the concretion confifls of 

 pebbles of the prevailing calcareous rock. In this concretion, at 

 a very confiderable depth under the furface, was found the un- 

 der parts of a glafs bottle, uncommonly fhaped, and of great 

 thicknefs ; the colour of the glafs was of a dark green. 



YoL. LY. B b In 



