^42 Mr, HuNTER*s Anatomical Remarks 



ill the Leach, Polypi, &c. may depend upon fome circumf^ance iii 

 the animal oeconomy which we are at prefent not fully ac- 

 quainted with. 



The univalves, whofe bodies are under (imilar circumftances 

 refpefting the (hell with this animal, have the intefllne refledled 

 back, and the anus, by that means, brought near to the exter- 

 nal opening of the fliell, the more readily to difcharge the ex- 

 crement ; and although this {IrutSture, in thefe animals, appears 

 to be folely intended to anlwer that purpofe, yet when we find 

 the fiuTie ftrufture in the black Snail, which has no fhell, this 

 reafoning will not wholly apply, and we mufl: refer it to fome 

 other intention in the animal oeconomy. « 



In this animal we mufl: therefore reft fatisfied that the difad- 

 vantagebus fituation of the anus, with refpe£l to the excrement's 

 being difcharged from the fhell, anfwers fome purpofe in the 

 oeconomy of the animal, which more than counter-balances the 

 inconveniences produced by it. 



It would appear, from coniidering all the circumftances, 

 that the excrement thrown out at the anus muft pafs from the 

 tail along the infide of the tube, between it and the body of 

 the animal, till it comes to the external opening of the fhell, as 

 there is no other evident mode of difcharging it. 



How the tube or fhell is formed in flone or coral is not eafily 

 afcertained. It may be afked, whether this animal has the 

 power of boring backwards as the Teredo Navalis probably 

 does, or whether the ftone or coral is formed at the fame time 

 with the animal, and grows and increafes with it : and if we 

 confider all the circumftances, this laft would appear to be moft 

 probable, and agree beft with the different pha^nomena ; for the 

 coral is lined with a fhell, which could not be the cafe if the 

 animal was continually increaiing this hole, both in length and 



I breadth. 



