63 



cular proprietor, is surrounded by a low barrier made of 

 planking or preferably of wire netting set in a wooden 

 frame, rising not more than 4 to 4^ inches above the 

 ground level (PI. V., fig. 17 and PL VI., fig. 19). To the 

 upper edge of this and at right angles to it a narrow 

 plank of thin wood 2\ to 4 inches wide, is nailed by one 

 margin in such a way that the remainder projects outwards 

 and away from the park. 



To secure the vertical barrier from displacement as 

 well as to prevent crabs tunnelling beneath, it is neces- 

 sary to imbed the lower edge several inches in the soil. 

 This device is very practical and effective (see fig. 6). 

 Crabs find it impossible to climb over, falling back 

 whenever they attempt to pass the horizontal outwardly 

 projecting plank. 



The cost of this protective device in wire netting 

 runs about 3 annas per yard ; an all-wood barrier costs 

 less but requires more frequent repair. 



The traps used to supplement blindage by capturing 

 the crabs which tend to congregate along the outer 

 margin of the protective barriers are of two kinds. One 



Fig. 7. — Section of Box-trap for Crabs. 



p. Sloping Fassage into Trap ; 



/. Hinged Door or Flap at inner End of Fassage ; 



h. Hinge. /. Service lid ; b. Bait. 



