170 



LIFE BY THE SEASHORE. 



KEY FOR IDENTIFICATION OF CRUSTACEA DESCRIBED 

 IN THIS CHAPTER. 



DECAPODA (Crustacea with\ I. NATANTIA (swimming forms). 

 ten pairs of legs) . . f II. REPTANTIA (creeping forms). 



I. NATANTIA. Family Carididne (shrimps and prawns). 

 Body depressed, rostrum" 

 rudimentary . 



Body compressed, 

 well developed 



\Crangon (common shrimp). 



Antennules with 

 filaments . 



Antennules with two fi\B.-\Pandaltis. 

 ments . . .) Hip^olyte. 



Filaments of antenmiles^ 



long and sub-equal, \ Panda iu<* 

 first pair of legs very K ' 

 long and slender . J 



Filamentsofantennules 

 short, one thick and 

 curved, the other 

 slender and straight, 

 first pair of legs short 

 and distinctly che- 

 late 



Hippolyte 



f Rostrum curved, with eight 

 or nine teeth above, and 

 five or six beneath P. 

 serratus. 



Rostrum straight, with 

 seven or eight teeth 

 above, and three beneath 

 P. squilla. 



Rostrum very long, curved 

 upwards, anterior half 

 without spines, except for 

 a very small one near the 

 apex P. annulicornis. 



Rostrum with two spines 

 above and two below 

 //. varians. 



Rostrum with three spines 

 above, and a terminal 

 notch, none below H. 

 cranchii. 



NOTE ON DISTRIBUTION. 



Little need be said on this point in addition to what is noted in the 

 text. Prawns, generally speaking, are commoner on the South and 

 West than on the North and East, and Palcemon serratus, at least, is 

 not likely to be found on the East Coast. But as the prawns are better 

 adapted for life in the open than between tide-marks, the occurrence 

 of large specimens in the latter situation is somewhat exceptional at 

 any part of the coast. The species of Hippolyte, which are small, are 

 common in rock pools, H. varians in most places round the coast, 

 //. cranchii on the South and West. I found it especially abundant 

 in the shore pools at Lynmouth, on the coast of Devonshire. Other 

 species of Hippolyte also occur. The common shrimp is found, where 

 the conditions are favourable, at all parts of the coast. 



