192 



LIFE BY THE SEASHORE. 



KEY FOR IDENTIFICATION OF ABOVE CRUSTACEA. 



II. REPTANTIA, creeping forms including lobsters, hermit-crabs and 

 their allies, and true crabs (see next chapter). For full definition of 

 Reptantia, see p. 163. 



Of the five pairs ^ 



1. Fa,, AstacM,. 



2. Fara. 

 ridse. 



Pal inn - 



3. Fam. Porcel- 

 lanidae. 



(chelae) 



None of the legs \ 

 bear forceps . J 



One pair of legs , Tail fan present, -\ 

 only with for- abdomen sym- V 

 ceps. Last pair I metrical .J 

 of legs or 1 No tail fan, ab- /-Tail long and . v -n i 

 last two pairs domenunsym-{ soft . . 4. Fam. Paguridae. 

 aborted . * metrical . ^Tail intumed 5. Fam. Lithodidre. 



, Fam. Corystidae 

 (distinguished 

 from true crabs by 

 long antennae and 

 leg-like maxilli- 

 pedes). 



Common lobster, Homarus 

 vulgaris. For specific char- 

 acters see text. 



Norway lobster, Nephrops nor- 

 kidney-shaped . / vegicus. See text. 



One pair of legs^ 

 only with for- I 

 ceps. All legs | 

 normal . J 



1. Fam. Astacidae. T Rostrum short, 

 Long - tailed J eyes rounded . 

 forms with largel R ^ , 



antennal scale . I 



2. Fam. 

 ridae 



[ 

 - 



Spiny forms witrn 

 Palinu- long antennules ! 

 .j and no antennal | 

 I scale . .J 



3. Fam. Porcel- 

 lanidae. Last 

 pair of legs re- 

 duced to rods . 



^Carapace ovate, 

 with distinct, 

 rostrum Gala- 

 thea 



Carapace nearly 

 circular, with- 

 out distinct ros- 

 trum Porcel- 

 lana . 



Rock lobster, Palinurus vul- 

 garis, the only British 

 species. 



In G. squamifera the meropo- 

 dite (p. 174) is longer than 

 the ischiopodite, and bears 

 one large terminal spine and 

 five little ones. 



In G. strigosa the ischiopodite 

 is longer than the meropo- 

 dite, which bears two 

 spines. 



'In P. platycheles the body, and 

 especially the chelipeds, are 

 covered with hair. 



In P. longicornis the body and 

 chelipeds are smooth. 



