REMARKS ON THE COLEOPTERA. 240 



rium of forms is still preserved, but where the general arrangement is 

 totally different, the prominent groups of one continent being either 

 feebly represented on the other, or else entirely wanting. 



It does not become us, in the present imperfect state of tropical 

 exploration, to determine what groups are peculiar to each continent ; 

 we can merely say that particular forms are more abundant in certain 

 regions. For by a strange fatality, (at least in Coleoptera,) no sooner 

 is any group admitted by a common consent to be exclusively Amer- 

 ican, than suddenly, as if produced by the well-known jugglery of 

 those countries, a species starts up in Central Asia, or Africa, (e.g., 

 Galerita, Agra, Sandalus.) Still, enough remains to show us that 

 the prevailing character of tropical fauna is individuality ; the 

 production of peculiar forms within limited regions : while the dis- 

 tinguishing feature of temperate and arctic fauna is the repetition of 

 similar or identical forms through extensive localities. 



On proceeding now to illustrate these deductions by special exam- 

 ples from the catalogue before us, it will be seen that the parallelism 

 of species in temperate and frigid climates can be demonstrated more 

 particularly in the genera which are more universally diffused over 

 the earth, or in those which are especially confined to temperate re- 

 gions, than in such as receive their principal development within the 

 tropics. Thus for instance, among the great group of Carnivorous 

 Coleoptera, the terrestial species, (although well represented in cold 

 climates,) contain an immense number of genera, each of which 

 (with few exceptions) seems to have a particular locus, external to 

 which it is feebly represented. Accordingly in this group, the par- 

 allelism of species is by no means clear, and the forms are rather to 

 be considered equivalent than analogous. On the other hand, 

 among the aquatic Predaceous Coleoptera, the genera are but few, 

 and the tribe is more abundant in cold regions ; and in these the 

 parallelism is most exact, so that there are but few mentioned in the 

 preceding pages, that have not their exact counterparts in Europe. 

 The characters appended to the new species will render this sufficient- 

 ly obvious to the student, while the relations of those previously 

 described by Kirby and Aube have already been clearly pointed out 

 by those authors. 



Passing on to the other water-beetles, the species of Helophorus 



