3O2 HISTORY OF THE EUROPEAN FAUNA. 



The beetles Rhopalomesites Tardyi, Eurynebria 

 complanata, and Otiorrhynchus auropimctatus also 

 belong to this fauna, as also the Earthworms Allolo- 

 bophora veneta and A. Georgii, and the Millipede 

 Polydesmus gallicus. 



It will be evident to every one from these few 

 instances of Lusitanian species, that somewhere in 

 South-western Europe and. North-western Africa, 

 and also, perhaps, in a larger now submerged western 

 land-area, there existed an active centre of develop- 

 ment, from which animals spread in all directions. 



If the presence of Platyarthrus in North-west Africa 

 proves that the Straits of Gibraltar had come into 

 existence after its southward migration, it also 

 suggests that the ancestral home of this woodlouse 

 was in the Spanish peninsula. Whether this sup- 

 position is correct or not, does not affect the Straits 

 of Gibraltar problem, for in a migration northward 

 into Spain from Morocco a land-connection would be 

 equally necessary. Almost every group of vertebrates 

 and invertebrates furnishes instances of species which 

 must have crossed the Straits on dry land. Many 

 naturalists have come to this conclusion, and have 

 clearly expressed their views on the subject At 

 the commencement of the present period, says Mr. 

 Bourguignat (p. 354), the north of Africa was a 

 peninsula of Spain, the Straits of Gibraltar did not 

 exist, and the Mediterranean communicated by the 

 Sahara with the Atlantic. 



The faunas of North-west Africa and the south- 



