164 Marine Investigations in Sonth Africa. Vol. V. 



eich tentacle when it is viewed from the oral side of the animal and 

 with the lophophore fully expanded. The result would be, of course, 

 that particles, in contact with the one side only, would be carried in a 

 direction outwards or inwards, and opposite to that of the apparent 

 motion of the 'cilia (due, of course, to the slower stroke in that 

 direction). The cilia on either side could be brought into contact 

 with the particles by rotation of the tentacle, which was observed in 

 a few cases to occur, but this point was not conclusively established, 

 as exact observations are not here easily made. It is certain, how- 

 ever, that the propulsive action of the cilia is not only towards the 

 mouth, as has been supposed, but is largely concerned in carrying 

 away any rejected particles. Particles of a diameter about equal to 

 a sixth of that of the tentacle, and larger, are carried off in this way, 

 as are also irregular masses of debris that may be caught up in the 

 inhalent current. Smaller pai'ticles are got rid of in another way. 

 If an actively feeding animal be viewed laterally, so that the outer 

 and basal part of the tentacles is seen, a large number of particles is 

 observed to be escaping between the bases of the tentacles over the 

 edge of the " membrane " connecting them, and then to fall in a con- 

 tinuous shower on to the edge of the tube, to which some were 

 observed to adhere (probably the origin of the inclusion seen in the 

 substance of the protruding part of the tube). 



Another and different action of the tentacles was observed when 

 the animal was feeding actively. This was a sudden bending in 

 towards the mouth of the distal free end of the tentacle both of the 

 inner and outer row [cf. fig. 1, in which one tentacle of the outer 

 row shows the nature of this bending). Single tentacles, indepen- 

 dently of the others immediately next them, showed this movement, 

 which was sharp and definite both in the action and recovery to the 

 normal position. At times this movement was repeated by different 

 tentacles at very short intervals, and in the case of Phoronopsis, in 

 which this movement was more marked, on several occasions it 

 appeared as a quite continuous jaculatory movement all round the 

 lophophore. It might be suggested that the result of this movement 

 is to throw or sweep particles of food towards the mouth, but only 

 in a few instances was this actually seen, and the possibility is not 

 excluded that these cases were accidental. This movement might 

 be compared to the reaction on stimulus of the tentacles of some sea 

 anemones and polyzoa. 



The inhalent current, which sets in towards the mouth region, 

 passes off in two directions, viz., between the outstretched tentacles 

 of the outer row^ and downwards, and between the tentacles of the 

 inner row and inwards, where there is formed a very strong current 



