On the Geoyraphlcal Dislributivn oj Insects. 181 



form. Sometimes a group may have all its elements concen- 

 trated on a single point of greater or less extent ; this is the 

 case with such as are endemical, at other times they may be 

 dispersed over so extensive a territory, that it would be ditfi- 

 cult to say where the group has its metropolis ; this takes place 

 Avith the kinds which are eminently sporadical. li we sup- 

 pose these groups to cross and intermingle with each other m 

 every way over the surface of the globe, which they embrace 

 ■IS a net it will be understood that although we may m some 

 degree conceive such a picture, it is impossible to render it 



visible to the eyes. . ^ 



Every family, however poor it may be m species, mrnishes 

 a proof of what has just been stated ; that of the Carabid^ one 

 of the best known, may be taken as an example. All are 

 aware that its province extends over the northern and tempe- 

 rate parts of the Old Continent, where it occupies a zone com- 

 prised nearly between the 68" and 43° north latitude. Thence 

 L ramifications extend over all the globe, ceasing.only where 

 vegetable life terminates : but its tribes for the most part shew 

 a tendency to establish themselves in other places than where 

 it has its principal seat, some of them at considerable dis- 

 tances from it. The Simplicipedes, Harpalid^, and Sabuli- 

 palpes are the onlv tribes which have the gi-eater number of 

 their species in the zone above indicated ; the Feronidae and 

 the Truncatipennes seem to be nearly ecpially divided among 

 the different regions of the globe ; the Ciciudelidae have only 

 two genera (Cicindela and Megacephala) in the zone m ques- 

 tion ; all the rest are proper to intertropical regions, and al- 

 most equally shared between the Old and the New Conti- 

 nent ; finally, the Scaritides and the Patellimanes have their 

 nrincipal seat in the warm countries of the old world. When 

 viewed, however, in groups inferior to that of a family, the 

 greater part of these tribes yield to the latter m respect to 

 their sporadicity. Such in particular is the family of the 

 Scaritides, which, if we were to deduct the genus Clivma 

 which extends to the Arctic Polar circle, would be deficient 

 throughout the old world beyond the 45" north latitude. On 

 .arriving at the genera, the matter becomes st.l more ob- 

 Some of these appear eminently sporadical, although 



vious. 



