112 THE ZOOLOGIST. 



access to four of them. One, after being submitted to a second 

 bout of hammering, was picked up, shaken violently, even 

 passionately, and then thrown away. To have four failures 

 out of seven attempts is bad, and, though it is not truly repre- 

 sentative, yet the average must be high, much higher than with 

 Mussels, Limpets, &c. With these, if one may put it so, the 

 Oystercatcher has a reasonable prospect of success, provided 

 that it attends to what are presumably the conditions of success, 

 and it can satisfy its wants with great rapidity. On the other 

 hand, the Oystercatcher has no security whatever that it can 

 open a Purple-Shell, and the process is apt to be infinitely 

 tedious. The seven shells in the example I have given were 

 dealt with in the space of about twenty minutes. In the same 

 time an Oystercatcher can account for seven times seven Mussels 

 with a fraction of the labour expended. 



It may be noteworthy that the Oystercatcher appears in- 

 variably to carry the shell crosswise in the bill from the place 

 where it was found to the place where it is to be opened, and yet 

 holds it by the outer lip in making any subsequent movements. 

 The relation of the bill to the aperture and the margin of the 

 first opening during the application of force to the shell is 

 also a little obscure. It is clear — in theory, at least — that if 

 the shell be held firmly the under side will be crushed and im- 

 paled in the soft parts which are generally refused in that con- 

 dition by the Oystercatcher. The evidence, however, both direct 

 and indirect, points the other way. When it is hammered the 

 shell does not rise with the bill between two successive blows, 

 and it appears to have a slight mobility independent of the 

 movements of the bill. The fragments are driven out and not 

 inwards, which, in consideration of the mechanical construction 

 of the shell, is by far the better plan. On the assumption that, 

 to produce the desired result, the shell must be held loosely, it 

 would seem simpler and more effective to put the point of the 

 whole bill inside the shell, but I have not been able to assure 

 myself that the Oystercatcher ever does so. At present, I 

 suppose that the lower mandible is kept outside the shell for the 

 express purpose of preventing or arresting any tendency to 

 lateral movement. As long as the shell is rocked in the direction 

 of its length it is perfectly steady, but its behaviour is uncertain 

 whenever the movement takes the line of its shorter axis. 



