The author commences this paper with a general description of the 

 present state of the Temple of Serapis, and gives the measurement 

 of the three marble columns which remain standing, and which, 

 from the height of 11 feet to that of 19, are perforated on all sides 

 by the Modiola lithophaga (of Lamarck) ; the shells of that animal 

 remaining in the holes formed by them in the columns. A de- 

 scription is then given of the present state of twenty-seven portions 

 of columns, and other fragments of marble, and also of the several 

 incrustations formed on the walls and columns of the temple. 



The conclusions at which the author arrives are — 



1. That the temple was originally built, at or nearly at the level 

 of the sea, for the convenience of sea-baths, as well as for the use 

 of the hot spring which still exists on the land side of the temple. 



2. That at some subsequent period the ground on which the 

 temple stood subsided slowly and gradually ; the salt water, entering 

 through a channel which connected the temple with the sea, or 

 by infiltration through the sand, mixed itself with the water of the 

 hot spring containing carbonate of Hme, and formed a lake of 

 brackish water in the area of the temple, which, as the land sub- 

 sided, became deeper, and formed a dark incrustation. 



The proofs are, that sea-water alone does not produce a similar 

 incrustation ; and that the vi^ater of the hot spring alone produces 

 an incrustation of a different kind ; also, that Serpulse are found ad- 

 hering to this dark incrustation ; and that there are lines of tioater- 

 level at various heights, from 2-9 feet to 4-'6 feet. 



3. The area of the temple was now filled up to the height 

 of about seven feet with ashes, tufa, or sand, which stopped up the 

 channel by which sea- water had been admitted. The waters of 

 the hot spring thus confined converted the area of the temple into 

 a lake, from which an incrustation of carbonate of lime was depo- 

 sited on the columns and walls. 



The proofs are, that the lower boundary of this incrustation is ir- 

 regular; whilst the upper is a line of water-level, and that there are 

 many such lines at different heights ; — that salt water has not been 

 found to produce a similar incrustation ; — that the water of the 

 Piscina Mirabile, which is distant from the sea, but in this imme- 

 diate neighbourhood, produces, according to an examination by 

 Mr. Faraday, a deposit almost precisely similar ; — that no remains 

 of Serpulas, or other marine animals, are found adhering to it. 



4. The temple continuing to subside, its area was again par- 

 tially filled with solid materials ; and at this period it appears to 

 have been subjected to a violent incursion of the sea. The hot- 

 water lake was filled up, and a new bottom produced, entirely co- 

 vering the former bottom^ and concealing also the incrustation of 

 carbonate of lime. 



The proofs are, that the remaining walls of the temple are 

 highest on the inland side, and decrease in height towards the sea- 

 side, where they are lowest ; — that the lower boundary of the space 

 perforated by the marine Lithophagi is, on different columns, at dif- 



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