114 



MADRAS FISHERIES BULLETIN 



VOL. XIV, 



and of suddenly wrenching themselves clear with a quick jerk 

 and a vicious lash of the opercular claw ; a nasty wound can be made 

 by this weapon in the case of the larger species. 



The Scorpion-shell or Five-fingered Chank {aiveral 

 s..',n»u, Tamil), Ptcroccra lainbis, is the most common species of this 



Fig 7. The Five-fingered Chai.k ( F. lawtis L.). 



genus in our waters. It is extremely abundant in the faunistically 

 rich weedy shallows of the south-western angle of Palk Bay. The 

 size when adult is considerable ; a length of seven inches is quite 

 common, and the width, if we include the long fingers, is fully half 

 this measure. In the immature condition the shell looks like an 

 ordinary stromb, and only when it attains full size does it form the 

 great " fingers " which are its characteristics. These are chan- 

 nelled on the lower side, processes of the mantle passing along the 

 channels, until they attain full size, when the channels close and 

 the " fingers " become solid. 



From low water to two fathoms, this shell is often numerous, 

 particularly along the coast between Pamban and Tondi. Some 

 are collected by the shore people wading in the sea at low tide, but 



