272 Mr. Swainson's Monograph 



other hand, it is not improbable, that time and reflection may dis- 

 cover remedies, which, at the outset, may not occur, 

 Bristol, November, 1 824. 



N. B.— Mr. Jefferys has taken out a Patent for this Invention; 

 and we understand that its efficacy has been very satisfactorily 

 proved by experiment. The draught of air through the furnace 

 was prodigiously increased ; and although the ascending column 

 of smoke was rendered as dense and black as it could well be 

 made, yet not a particle of smut or smoke was observed to escape 

 by the vent at the bottom of the water-flue. A strong current of 

 air, and a stream of black water issued forth, but nothing like 

 smoke. 



Art. V. A Monograph of the Genus Ancillaria, with De- 

 scriptions of several new Species. By William Swain- 

 son, Esq., F.R.S., F.L.S., M.W.S.,(^"C. 



Having been requested to ascertain the names of several fossil 

 Ancillarise, brought from the neighbourhood of Grignon, and finding 

 some difficulty in recognising other recent species mentioned by 

 modern writers, I have beenledtoa general examination of the ge- 

 nus. The result of my observations is contained in the following 

 paper, in which I shall endeavour clearly to define the four receat 

 species mentioned by Lamarck, uniting to them others which are 

 either altogether new, or placed under analogous genera. 



The extention of the genus which I shall thus propose, will not, 

 however, require any material alteration in its characters, as defined 

 by M. Lamarck, in theAnimaux sans Vertebres, torn. 7, p. 412. 



In determining the species, I have been principally guided by 

 the number, proportion, and mode of sculpture observed in the 

 lines or grooves, and by the transverse callous belts, which encir- 

 cle the base of all the Ancillarite ; this latter character likewise be- 



