WHEEL-BEAREES. 233 



like jaws open wide and stretch forward to grasp the little 

 victim (which is still distinctly visible through the trans- 

 parent tissues) : they touch the globular envelope, but 

 cannot quite grasp it. The Brachion redoubles its efforts ; 

 the jaws gape vigorously, but can only scrape the sides of 

 the little globe, which at every touch slips away, the expanse 

 of the jaws being not quite sufficient to embrace it. 



At last the little animal becomes indignant ; the jaws 

 no more endeavour to grasp, but with a very distinct and 

 sudden upward jerk throw out the prey, which until now 

 has been retained and pressed downward by the contrac- 

 tion of the sides of the sensitive throat. Strange to see, 

 the little Syncrypta, after all its imprisonment and rough 

 handling, is no sooner free than it whirls merrily away, 

 revolving as it pursues its even ciliary course, just as if no 

 interruption of its freedom had occurred. 



Meanwhile, however, better success attends the Bra- 

 chion's hunting ; for a smaller globe has sunk into the 

 throat, and passes with a gulp into the mouth, between 

 the gaping jaws, which instantly close upon it, and, working 

 vigorously, bruise it down with a hammer-like action upon 

 a sort of central table. After this process has gone on 

 for a few minutes, the green mass, less perfectly denned 

 than before, slips through a narrow postern-gate, along a 

 short slender alley, into the digesting stomach. 



But what sort of a mouth is this ? It is inclosed within 

 the tissues of the body, not very far from its centre, so 

 that no part of it comes into contact with the external 

 water, or even approaches any portion of the superficies of 

 the body. It has been usual to call the great hemispheric 

 bulk in which the symmetrical hammers work so vigor- 

 ously, a gizzard ; but it is a true mouth, and the hammers 

 are true jaws. 



This form of mouth is termed a mastax ; it consists of a 

 dense but transparent muscular mass, forming three lobes 

 at its lower part, deeply cleft at the front of its ventral 



