26 



LIFE BY THE SEASHORE. 



species work, and for this habits of patient and minute 

 observation are essential. It is necessary, also, to emphasise 

 the necessity for handling specimens freely. The healthy 

 child instinct to touch everything seen is so thoroughly 

 educated out of most people, that they never seem to realise 

 how enormously sense impressions are strengthened when 

 hand and eye work in combination. In studying zoology, 

 therefore, from the first train your fingers. 



The preliminary study recommended in the case of 

 limpets may be equally well carried out with the different 

 kinds of crabs. The hard coat of the crabs, which gives 

 perfect consistency to the form, renders them particularly 

 well fitted for the present purpose. On every shore two 

 kinds of crabs are almost certain to be found : these are 



the common shore crab 

 (Cardnus mamas, see 

 Fig. 49, p. 153), and the 

 edible crab (Cancer 

 pagurus}. The former 

 on the tidal rocks will 

 be found most in evi- 

 dence, but small forms 

 of the latter are usually 

 very abundant, especi- 

 ally far out, and those 

 who know where to 

 look will not fail to 

 find examples of quite 

 considerable size. The 

 young of the shore crab are extraordinarily variable in colour 

 they change, indeed, according to their surroundings 

 while the colours of the young edible crabs are much more 

 constant, though often quite unlike those of the adult. It 

 is not necessary to discuss in detail the differences between 

 the two forms ; there are probably few people who could not 

 recognise an adult edible crab when they see it. Unless, 

 however, your perception of form is much stronger than 

 your perception of colour, you will probably find that the 

 colour variations of the young confuse your judgment, and 

 that you have some difficulty in settling the nature of a 

 handful of small crabs gathered at random. If this is so, 



FIG. 8. Edible crab (Cancer pagurus). 



