INVERTEBRATE ANIMALS. 69 



the Prawn is generally keeled and extended in the form 

 of a sharply-toothed beak, but in the Shrimp is depressed 

 and unarmed. Prawns whilst living are objects of great 

 beauty, and in warm climates often exhibit vivid colours 

 and attain a large size. Mr. Gosse notices the curious 

 fact that Prawns taken from the obscurity of deep holes 

 and rocky pools reflect a rich flush of iridescent purple 

 extending over the whole body, heightening in effect the 

 various streaks and spots of orange, light-blue, red, 

 chestnut, and cream white which adorn the animal. 

 These disappear, though the animal may continue in 

 health, after a few hours' exposure to the light ; but 

 specimens captured from shallow pools have, even when 

 first taken, all their markings of a pale-olive tint. 

 Estimated number of species, 42 (M. Edwards) ; 

 British, 11 (Bell). 



U Examples of Rhynchoclnetes, H'qjpolytc, and 



Palcsmon, including P. carcinus and P. Jamai- 



cencis. 



Group 168."Families CRANGONID^, ALPHEID^, and 

 PENiEID^. Shrimps, Cramjoii, exhibit a tendency 

 the reverse of that noticed in Prawns, the species found 

 in northern seas being frequently larger than those 

 belonging to the more southern coasts of Britain. In 

 the arctic seas and in the bays of Spitzbergen they 

 supply food to the Walrus and the Seal (Adam White). 

 Estimated number of species : recent, 52 ; British, 10, 

 (Bell). 



^ Examples of Crangon, Atya, Sicyonia, Alpheus, 

 including Crangon borealis. 



This group, together with the preceding = Famille 

 des Salicoques (M. Edwards). 



