164 BY THE DEEP SEA. 



thumb" a few minute grains of sand and carefully introduces 

 them into this auditory chamber, where they mix with some 

 fine hairs or cilia, and their agitation when acted upon by 

 sound-vibrations transmits sensation to the nerves The third 

 joint gives support to two lashes or " horns," one of which in 

 this species is branched. 



The basal joint of the second antennae also bears a flattened 

 scale that is enormous, being three-quarters of an inch in 

 length and a quarter of an inch in breadth. There is but one 

 lash (flagelluni) to this external antenna, and this strong, long 

 organ measures over six inches in full-grown specimens ; that 

 is, one and a half times the extreme length of the Prawn from 

 the tip of the forbidding rostrum to the extremity of the tail. 



We have mentioned the two pairs of "hands" (chef as), and 

 behind these are three pairs of long and slender walking feet. 

 Then, further back, beneath the abdomen, there are five pairs 

 of swimming organs, and to these in the female the eggs are 

 attached. The tail-fan must not be forgotten ; it is a beautiful 

 and most effective organ. The four plates of which it is com- 

 posed are finely fringed with delicate hairs, and are so hinged 

 that they can be partially closed one over the other, or fully 

 expanded to have greater power when opposed to the water. 

 It is by means of this valuable organ that the Prawn takes 

 those astonishingly rapid backward leaps which make him 

 hard to be caught either by man or smaller enemies. 



Before leaving the Prawn, I would like to say that our 

 portrait of him does not pretend to show the length of his 

 antennae ; and it would be well to make clear how he carries 

 so many to be useful to him. He is always waving these 

 about, and there can be little doubt that he receives impres- 

 sions through their agency, olfactory and otherwise. It does 

 not matter how far away a Prawn may be ; if you give an 

 anemone a small portion of food, and there is a Prawn at the 

 far end of the tank he will know it, and will come prancing up 

 to the right neighbourhood. But his olfactory sense though it 



