THE RIBBON SAW. 



245 



with comparative ease. To those who have been accustomed to 

 cutting fretwork with the slow hand-saw, the Cordon Saw is 

 simply fascinating, the slender steel ribbon cutting through the 

 wood with wonderful rapidity and very little sound. 



BEAUTIFUL as this invention is, it was long ago anticipated 

 in Nature ; and the Cordon Saws, which we shall now see, are 

 armed with teeth many more in number, and far more compli- 

 cated in detail, than those of any saw made by the hand of 

 man. I allude to the Tooth-ribbon possessed by many of our 

 common molluscs, such as the Limpet, the Whelk, the Peri- 

 winkle, the Slug, &c. The last mentioned of these creatures 

 possesses a natural Cordon Saw with nearly twenty- seven thou- 



PORTION OF TOOTH -RIBBON OF WHELK 

 (HIGHLY MAGNIFIED). 



RIBBON OB CORDON SAW. 



sand teeth, and scarcely a tooth that is not elaborately cut into 

 secondary teeth. 



As all these creatures have their teeth differently formed and 

 set, according to the species, it will be impossible to describe 

 them separately. I will therefore restrict myself to the Tooth- 

 ribbon of the common Whelk, a specimen of which is now 

 before me. When viewed through the microscope, it is found 

 to consist of a flat membranous ribbon, on which are set three 

 rows of teeth, those of the outer row being hooked, and those 

 of the inner one plain. 



The outer teeth are formed somewhat like the Hebrew 

 letter 3, both of the points being very sharp, and the central 

 part being furnished with two secondary teeth. All these 



