194 



MEDITERRANEAN PROVINCE. 



African, but which have not as yet been observed 

 within that internal sea. These, like the American 

 forms, have to be deducted when the fishes of the 

 external Lusitanian province are compared with 

 those of its Mediterranean portion. The known 

 fishes of this sea are 444, and of these as many as 

 150 at least range the Atlantic as high as our 

 south-western coasts, and seventy are met with 

 about the Atlantic islands. If we compare the 

 numbers of the Mediterranean fishes with our own 

 (p. 119), we find that an, interval of twenty degrees 

 of latitude across the whole Lusitanian province 

 gives still as much as twenty 'per cent, of common 

 forms. This is a very low rate of change in space 

 with respect to the distribution of species ; but it is 

 quite high enough to satisfy us (in the absence of 

 any definite information respecting the fishes of the 

 Atlantic coasts of Spain and Portugal) that, so far 

 as calculation can be applied to such questions, 

 there exists a very high degree of probability that 

 all the known species of Mediterranean fishes are 

 also Atlantic. 



It is but justice to Kisso, the naturalist of the 

 seas of Nice, that he should be mentioned as per- 

 haps the first who called attention to that distribu- 

 tion of marine life which is dependent on depth. 

 With reference to the great class of fishes, he ob- 

 serves that certain forms frequent the mouths of 

 rivers; that along the open coast-line the sub- 

 merged marginal rocks, covered with Fuc% Cera- 



