I02 MADRAS FISHERIES BULLETIN VOL. Xl\\ 



molluscs the shell is conical and forms a stony cap under which 

 the animal lives secure. The limpets have a broad sole-like 

 foot as in the chitons. This assists them greatly in clinging to 

 the rocks on which they have their home ; the broad muscular foot- 

 disc acts like a boy's leather sucker and by the total exclusion of 

 air beneath it, atmospheric pressure comes into play and has to be 

 overcome before the limpet can be pulled away from its foothold. 

 Atmospheric pressure amounts to 15 lb. to the square inch, and 

 the conical shape of the shell gives no grip to the fingers ; it is 

 well nigh hopeless to detach a limpet from a rock unless we can 

 take it unawares when the edges of the shell are raised slightly 

 off the rock, and slip a knife under, dislodging the animal by a 

 sudden wrench. 



Limpets live between tide-marks on rocky coasts. They are 

 not very abundant in India and are usually small. At Covelong, 

 Pamban, Mandapam and Cannanore, they may usually be found, 

 often so near to high tide level that the sea leaves them high and 

 dry for several hours twice a day. They feed upo)i the smaller 

 seaweeds and their habits are well worth watching. On coasts 

 where they abound I have often heard a continuous low rasping 

 hum rising from the rocks around. It was meal-time with the 

 limpets; a multitude were browsing on the tiny weeds growing on 

 the rocks, the noise arising from the file-like action of myriads of 

 minute teeth. The radula or dental ribbon of the limpet is longer 

 than the whole animal's body. In the common British limpet the 

 tongue has nearly 2,000 teeth set in about i6d rows of 12 teeth in 

 each. The hinder part lies coiled up like a watch spring. New 

 teeth are formed at the hinder end and the ribbon unrolls a little as 

 equired to make good the waste that goes on at the front end from 

 the wearing down of the teeth in use. Limpets have a well-marked 

 homing instinct anil though they may crawl several feet away from 

 their home, they return there regularly after their foraging ex- 

 peditions. In soft rocks they make quite a deep pit at the place 

 they choose as their home ; on hard rocks this spot is marked out 

 by its smoothness, and may even be a little lower than the 

 surrounding surface. 



In Europe the poorer classes in several countries (France, Italy, 

 Ireland, etc.) value the limpet as a cheap delicacy ; very large quan- 

 tities are eaten. At Covelong where they are more numerous than 

 I have seen anywhere else on the Madras coast, some of the poorer 



