270 FISHES. 



The Physostomes are nearly the same as in the British 

 district, viz. a Smelt {Mypomesus), probably also the Arctic 

 Mallotus, an Anchovy, several species of Clwpm, and the 

 Conger-eel. A very singular Salmonoid fish, Salanx, which 

 is limited to the north-western Pacific, occurs in great abrmd- 

 ance. 



Also, the Lophobranchs correspond in their development 

 to those of the British district, Nerophis being replaced by 

 Urocampus, 



Neither Myxinoids nor Branchiosioma have as yet been 

 found. 



2. The Japanese district is, like the Mediterranean, dis- 

 tinguished by a great variety of forms ; some of them are 

 peculiar to it (marked J. in the following list) ; others occur 

 in the Mediterranean, though also in other districts (M.) 

 The resemblance to the Mediterranean is even greater than 

 would appear from the following list of genera, inasmuch as 

 a considerable number of species are identical in both dis- 

 tricts. Three of the Berycoid genera have hitherto been 

 found in the Japanese and Mediterranean districts only, and 

 nowhere else. Another very singular fact is that some of 

 the most characteristic genera, like Mullus, Zevs, Calliony- 

 mus, Centriscus, inhabit the Mediterranean and Japanese 

 districts, hut have never reached the opposite American coasts, 

 either in the Atlantic or Pacific ; although, at least in the 

 latter, the oceanic currents would rather favour than ob- 

 struct their dispersal in the direction towards America. Bold 

 as the hypothesis may appear, we can only account for the 

 singular distribution of these shore fishes by assuming that 

 the Mediterranean and Japanese seas were m direct and 

 open communication with each other within the period of 

 the existence of the present Teleosteous Fauna. 



Gadoids have disappeared, or are represented by forms 



