SHRIMPS AND PRAWNS. 165 



helps him to this extent, appears to act best at a little distance 

 from the fragrant object. I have frequently observed a Prawn 

 come quickly to the locality where food has been introduced 

 and evince great excitement and interest ; but his sense has 

 not been fine enough to tell him at once the particular spot in 

 the locality where it lay. I have on such occasions seen him 

 walk over what he was seeking, whilst his hands were 

 nervously scraping the ground and casting around for the 

 delicacy he knew was close by. Now this is the order of his 

 antennae -bearing : of the first or internal antennae that lash 

 which has the short branch is carried half erect pointing out- 

 wardly, the companion lash pointing forwards, so that he 

 cannot run against any obstruction without knowing it. The 

 second or external antennae are borne with a slight curve 

 forward, then far abroad on either side. He is thus fairly 

 guarded by sensitive organs well-nigh all round. 



There are two other British species of Leander Z. squilla 

 and L.fabricii which occur in the rock-pools, and may easily 

 be mistaken for young specimens of L. serratus. The dis- 

 tinguishing feature is to be found in that awe-inspiring, saw- 

 edged rostrum that projects far in advance of the Prawn's* 

 head, and of which no one has yet discovered the purpose. 

 In the bonafide Prawn this has a very decided curve upwards 

 all the way, and on its upper edge it has seven sharp spines 

 closely following each other, with an eighth lagging a sixth of 

 an inch behind the seventh, and really on the carapace, not 

 the rostrum ; on the underside there are four close together in 

 the middle, and a half-hearted one midway between the first 

 of these and the tip of the rostrum. So much for the type ; 

 now for L. squilla. The rostrum is almost straight with a 

 slight upward curve towards its tip. Like its big relative it has 

 seven or eight teeth above, but two of these are really part of 

 the carapace, and there are only three spines below. The 

 second pincer-legs are not proportionately as robust as in the 

 Prawn, and the creature does not attain to more than half the 



