in the Lamellibranchiata, 181 



before. The pointed manner in which this is put may suggest 

 to some persons a doubt on the subject. But why should Dr. 

 Williams express so much surprise in this instance, when he 

 must know that Dr. Sharpey's discovery has been overlooked by 

 every subsequent writer on the ceconomy of the Lamellibranchiata 

 up to the present time ? Nay, there appears some reason 

 to believe that Dr. Williams himself may have been amongst the 

 number, for at the same Meeting of the British Association at 

 which our paper, now acknowledged to contain the true theory 

 of branchial action, was read, a paper by Dr. Williams on the 

 same subject was also read, in which it is stated as the result of his 

 researches, " That the branchial siphon acts in drawing in water 

 into the chamber of the mantle by the dilating of the valves of 

 the shell /' and " That a part of the water which is thus drawn 

 into the branchial chamber is swallowed, and eventually rejected by 

 the faecal orifice, and that the rest is expelled by the orifice in the 

 mantle, and in part by the branchial orifice*." Had Dr. Williams 

 been then aware of Dr. Sharpey's discovery of the passage of the 

 water through the gills, he could scarcely have had recourse to 

 the extraordinary idea that the water found its way into the 

 anal chamber through the intestine. Curiously enough, it is 

 announced in the same paper as another of the conclusions come 

 to, " That in Pholas the siphons are richly lined with vibratile 

 cilia, as well as the branchial plates." 



There can be no doubt, now that the passage is pointed out, 

 that Dr. Sharpey had got hold of the true explanation of the 

 branchial currents, in examining the common Mussel, and that 

 the right of priority must be assigned to him. That his dis- 

 covery has remained so long unnoticed probably arises, partly 

 from its being introduced under the head of ' Cilia/ where we 

 should not expect to find new views on the structure and ceco- 

 nomy of the bivalve mollusks, and partly from the modest man- 

 ner in which the facts are stated, without attention being drawn 

 to the points where they differ from the accounts of other ob- 

 servers. For ourselves it may be necessary to say, that we had 

 not seen the article by Dr. Sharpey, as in the library we consult 

 for books not in our own, that of the Literary and Philosophical 

 Society of Newcastle, the volume of the ' Cyclopaedia of Ana- 

 tomy/ containing the article ' Cilia/ was lost in 1848 (before we 

 turned our attention to the subject) and has never been replaced. 

 Had we known that it contained any original matter on the ceco- 

 nomy of the Bivalves, we should certainly have made a point of 

 procuring a sight of it, as we have done since the appearance of 

 Dr. Williams's remarks. 



* Report Brit. Assoc, for 1851, p. 82. 



