( 73 ) 



^the fliell on wliich it was placed (the ligament being in the middle of 

 it,) as if it were glued to the fliell ; and when I endeavoured to pull 

 off tlie ligament, I found, by feveral trials, that (though it was very 

 itrong and tough, in proportion to its fize) it would break before the 

 flat tliin membrane could be loofencd. 



Hereupon I recolledled, that wlien a boy, I had often amufed my- 

 felf with a play-thing which we called* " een Treck-lcertje." This 

 js afmall round piece of leather, about two inches in diameter, hav- 

 ing a fmall hole in the middle, through which was drawn a pack- 

 thread, with a knot at the end. This leather being firfi: foaked in 

 water, was placed flat on a ftone, and with this we could not only 

 lift up the ftone, but carry it to fome diflance. 



Now, upon the fame principle as the ftone adheres to the leather, 

 partly by the prelHire of the atmofphere, and partly becaufe no air 

 or water can gain admittance between the ftone and the leather, 

 thelikeeffe61: is produced in the coheiion or ftickb^ig of the membrane 

 I have been defcribins:. 



I have thought it proper to give a drawing of the ligament before- 

 mentioned, and its feveral branches : and in Plate III. j6^. 8, is flaewn 

 a part of it, which is cut off at A in the part which comes out of the 

 ftiell ; this in /^. 7, is fhewn at BE of its natural ftze. Iny?^^'-, 8, 

 F G H I K are feen the ramifications or branches, or rather a fmall part 

 of them ; and at L M is fliewn one of the fhort liganients, with its 

 membrane NOP, the ligament here appears on the upper fide of the 

 membrane, in like manner as if the latter was fixed to fome other 

 ihell ; and here are to be feen the many parts whereby the ligament 

 is joined to the membrane, which latter alfo appears fomewhat ele- 

 vated at the place of joining, 



*That is, in Englifh,a pulling or drawing-leather ; it is a common play-thing among boys 

 .inJinglandj.and is called by thcra a fucker. 



