16 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



from side to side ; and when charged with food, it is 

 withdrawn into the stomach, unloaded, and again 

 put forth." Mr. Peach says : " The mark left on the 

 face of the rock coated with a film of fine sea- weed 

 after grazing resembles the track of a sea-worm."* 

 After long and close watching I never could see it 

 thrust out its long tongue from side to side, and I 

 am strongly impressed that it never does so. That 

 part of the tongue that lies behind the lij^s, and 

 ^vhich is never protruded beyond them, ai)X3ears to 

 be the only portion applied to the cropping of the 

 filamentous algse while browsing. 



The portion of the tongue lying in the mouth is 

 furnished ^vith ro^vs of strong, curved teeth, getting 

 weaker as they pass doTvn^vards ; and near the end 

 the tongue becomes transparent, and the teeth 

 almost indistinguishable and ill-fitted for cropping 

 and gathering in the food. 



When the animal is out broAvsing it moves on 

 sloAvly, turning slightly from one side to the other, 

 much in the manner of a cow grazing. At such 

 times the teeth on that part of the tongue lying in 

 the mouth are seen rasping on the side of the 

 vessel, and every stroke they make is heard so 

 distinctly on the glass as to be counted with ease. 

 These were found, after careful trials, to be from 

 38 to 42 in the minute. The browsed marks made 

 are very irregular ; sometimes patches the size 

 of a six]3ence or a shilling cropped quite clean as 

 if swept off by the lips of the animal, and other 

 l^arts as if scratched by the teeth of a comb. I 

 have no doubt that these devious tracks made by 

 the mouth of the animal have been mistaken 

 for the work of the long tongue stretching out 

 from side to side and leaving its marks on the 

 small algae. 



Forbes and Hanley say : " When the limpet 

 moves about it makes upon the rock a curious 

 fucoid-like track of some breadth, probably caused 

 * Brit. Conch., iii. 232. 



