66 



chambers has been ably explained by Dr. Buckland in the Nautilus, 

 where the calcareous inflexible tube protecting the membranous si- 

 phon is not continuous. The working of the siphon is, however, less 

 intelligible in those species in which the outer calcareous tube is con- 

 tinued from chamber to chamber, as in the Spirulce, Orthoceratites , 

 &c., and it is \vith respect to camerated shells of this kind that I 

 would ask how far the reasoning suggested by the chambers in the 

 water Spondylus may be applicable in their case ; and whether a 

 finai inteution can be clearly traced beyond the diminution of specific 

 gravity occasioned by a large proportion of the shell being converted 

 into receptacles of gas ; if indeed we have sufficient evidence to as- 

 sume that they do not contain a denser fluid, likę the Spondylus. 



Mr. Owen placed upon the table, as illustrative of his observations, 

 sections of both valves of a large specimen of the Water-clam, and 

 also stated that Dr. Bostock had kindly undertaken to submit the 

 fluid contained in the chambers of the shell to a chemical analysis. 



Dr. Bostock being present laid before the Meeting the following 

 remarks upon the fluid in ąuestion. 



Mr. Owen having put into my hands, for examination, a fluid 

 \vhich was obtained from the cavities in the valves of the Spondylus 

 varius, I obtained from it the following results. 



It was turbid, had an acid saline taste, and a rank disagreeable 

 odour. After standing for twenty-four hours, it deposited a \vhitish 

 curdy sediment, and became clear and transparent. The clear fluid, 

 amounting to 54"'., was poured from the sediment, and \vas subjected 

 to various tests. It was neither acid nor alkaline; itproduced avery 

 copious precipitate ■vvith the nitrate of silver, indicating the pre- 

 sence of a large proportion of muriatic acid ; the muriate of barytes 

 indicated a slight trace of sulphuric acid, ■vvhile the appropriate tests 

 of lime, magnesia, and iodine produced no effect. A portion of'the 

 fluid was evaporated by a gentie heat, \vhen a ąuantity of crystals 

 of the muriate of soda was obtained, amounting in weight to very 

 nearly twenty per cent of the fluid, After the removal of the crystals, 

 a little brown matter was left in the capsule, but in too minute a 

 ąuantity to enable me to ascertain its nature and properties, except 

 that it was not soluble in alcohol ; we may, however, presume that 

 it gavę the fluid its peculiar flavour and odour. 



lt appears therefore that the fluid in ąuestion consisted almost en- 

 tirely of a solution of pure muriate of soda, d!fl'ering therefore, in its 

 chemical constitution, from sea--\vater. 



The sediment mentioned above I returned to Mr. Owen ; it ap- 

 pcared to consist of sraall globular or rather pyriform bodies, pro- 

 bably of an organic origin. 



