CRUSTACEANS 



From a dry county like Warwickshire one might not expect a great 

 abundance of animals so aquatically disposed and so essentially moisture 

 loving as the Crustacea. How small in fact any such expectation has 

 been down to quite recent times is pointedly illustrated by a volume of 

 much merit and usefulness. For the meeting of the British Association 

 in 1886 a Handbook of Birmingham was prepared, embracing a wide range 

 of subjects. The section devoted to zoology occupies in it satisfactory 

 space and prominence. A valuable page of this section is devoted to 

 crustaceans, but the writer of it has to explain how they creep into 

 this little corner of the field. They win their chance of notice it 

 appears not because they are members of an important independent class 

 of the animal kingdom, but as a subordinate branch of the district's 

 microscopic fauna. It is however a mistake to suppose that the carcino- 

 logy of a county is wholly dependent for its interest on an extensive 

 seaboard, or the presence of large lakes and broad rivers. Some 

 crustaceans have in the course of ages, if theory may be trusted, forsaken 

 that watery world in which alone their distant ancestors could breathe, 

 and, whether theory can be trusted or not, as a matter of fact their 

 existing generations live on land. Others there are among the fresh- 

 water species as modest in their views as Cincinnatus, who preferred his 

 little farm to a dictator's palace. They actually like a rivulet better than 

 a river, and disdainful of spreading lakes make it a point of honour to 

 swarm in small and shallow ponds. There are moreover a very great 

 number which, though incapable of active life on land, can in the 

 embryonic stage wait for water with admirable patience, choosing to be 

 born only when there is liquid for them to live in. 



For the crustaceans of an inland county it is sufficient to distinguish 

 two out of the three principal sections of the class, the Malacostraca 

 and Entomostraca. All the crabs, lobsters, shrimps and other forms 

 belonging to the former group are linked together by a community of 

 structure much closer than at the first glance would be imagined. 

 Leaving out of count the foremost piece to which the eyes belong and 

 the hindmost piece called the telson, there are in the malacostracan body 

 nineteen segments, and each segment has a pair of appendages assignable 

 to it. That appendages are often missing, that segments coalesce, making 

 two or more look like one, must be admitted. But the general state- 

 ment is based on very substantial evidence. The appendages, for 

 example, that are missing in one sex will be found in the other, or if 



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