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At Q R is r^prefenled another ligament, and at S T V its mem- 

 brane, with the concave part of it, appearing open, being in a con- 

 trary poiition to tlie former reprefentation. I have often feen this 

 cavity reach into the ligament as far as M or R, but otherwife it is 

 quite clofe and compact. 



Each of thefc I'gaments confifls of a great number of exceflively 

 fmall particles, wnich cannot be contemplated without the greatefl 

 admiration, efpecially when we recolle6t the power v/hich the Muf- 

 cle has of moving each of thefe ligaments, and alfo that the mem- 

 brane muft be placed quite fmooth and flat upon the fhell, to whicli 

 it is fixed, in order to caufe it firmly to adhere thereto. 



Now, if we farther confider that Mufcles, while in the fea, always 

 lie with that fliell upwards which they open occafionally, and that 

 their fliells (which are very thin) and their bodies together are but. 

 little heavier than the water wherein they live, and alio that many 

 of them at low ebb-tides are left deftitute of water, at which times, 

 in my opinion, much air muft inlinuate itfelf between their fliells, by 

 which means they become lighter than the water; they would then.: 

 be liable either with the ebb to be carried out into the deep, or by 

 the flood to be thrown upon tlie land, and fo w^ould perifli. But 

 provident Nature has taken care to preferve them in this refpe6l, 

 by furni filing them with a ligament, fpreading into various branches, 

 and at the end of each branch aji organ, which I have named a mem- 

 brane, by the help of which the Mufcles can fix themfelves either 

 to empty fliells, or other fubftances, or to one another, by wliiclv. 

 means they are preferved. 



But as my princii)al defign was to difcover, as far as poflible, the' 

 generation, or procreation, of thefe fifli, I come now to that part of 

 tiie I'ubjeft. 



I obferved, that thefe Mufcles, fome in a greater, and others in a 

 lefs degree, had the outfides of their fliells covered with a kind of 

 fubftauce, thinly fpread upon the fliell, and firmly adhering to it, or 



