NOTES AND MEMORANDA. 213 



two arms resolutely into an anemone (Anthea) and pull out a worm 

 which the anemone had closed over. In like manner a blind Stenor- 

 liynchus or Inachus will perceive a piece of worm when it has been 

 in the water a few minutes, and will then set out and find it. I 

 have seen them hunting about when worms have been put into 

 another tank from which water was flowing into their own vessel. 

 There can then be no doubt that these animals find their food by 

 scent, and it becomes difficult to determine what sort of objects they 

 can see. It is not even certain that they can see each other. If a 

 prawn is eating a piece of worm and another prawn finds it and takes 

 it away, the first prawn will again begin to quest wildly as at first, 

 and does not make for the prawn with the worm, though it may be 

 only a few inches off. Nevertheless, it is certain that prawns at all 

 events can perceive more than mere difference between light and 

 darkness, for they notice a hand or even a thin stick placed between 

 them and the light, putting out their antennae towards it. Stenor- 

 hynchus also will put up its anterior pair of walking legs when a fish 

 swims close over its head. It would appear that the eyes of these 

 creatures are particularly sensitive to shadows. If a worm is hung 

 by a thread in the water about eight inches from the bottom, the 

 prawns will first hunt on the bottom as usual, and will then begin 

 swimming about in quest, but on coming a few inches below the worm 

 they will rise to it directly. 



Though it seems probable that the sense of smell is obtained 

 through the antennules, in shrimps at all events it is not exclusively 

 so derived, for a shrimp with no antennules will hunt if a piece of 

 worm is put very near it. On the other hand, the antennge, of a 

 prawn at least, appear to have no such power, as prawns when 

 eagerly seeking food may be seen to touch it with their antennae 

 and still be unable to find it. 



As is well known, certain crabs, as Stenorhynchus , Inachus, Pisa, 

 and Maia, have the habit of fastening pieces of weed, &c., on their 

 backs and appendages until they are almost indistinguishable from the 

 surrounding weeds if there are any. In the case of Stenorhynchus 

 and Liachus I have often watched this process. The crab takes a 

 piece of weed in his two chelee, and neither snatching nor biting it, 

 deliberately tears it across as a man tears paper with his hands. 

 He then puts one end of it into his mouth, and, after chewing it up, 

 presumably to soften it, takes it out in the chelse and rubs it firmly 

 on his head or legs until it is caught by the peculiar curved hairs 

 which cover them. If the piece of weed is not caught by the hairs, 

 the crab puts it back in his mouth and chews it up again. The whole 

 proceeding is most human and purposeful. Many substances as 

 hydroids, sponges, Polyzoa, and weeds of many kinds and colours are 



