272 FISHES. 



3. The Californian district includes a marked northern 

 element, the principal constituents of which are identical with 

 types occurring in the corresponding district of the Atlantic, 

 viz. the North American, as exemplified by Discoholi, Anarr- 

 liichas, Cenironotus, Coitus, Hippoglossus, Clupea {harengus), etc. 

 But it possesses also, in the greatest degree of development, 

 some types almost peculiar to itself, as the Heterolepidina, 

 some remarkable Cottoid and Blennioid genera, and more 

 especially the Embiotocoids — viviparous Pharyngognaths — 

 which replace the Labroids of the other hemisphere. Gadoids 

 are much less numerous than in the North American district. 

 The southern forms are but little known, but it may be anti- 

 cipated that, owing to the partial identity of the Fauni3e of the 

 two coasts of the Isthmus of Panama, a fair proportion of 

 West Indian forms will be found to have entered this district 

 from the south. The following are the principal genera : — 



ChiTnmra, Galeus, Mustdus, Triads, Oestracion, Bhirux, Raja. 



Serranus ; Ohirus, Ophiodon, Zaniolepis ; Sebastes ; Nau- 

 tichthys, Scorpmnichiliys, Coitus, Centridermichihys, Hemilepi- 

 dotus, Artedius, Prionotus, Agonus ; Cyclopterus, Liparis ; 

 Anarrhichas, Neoclinus, Cebidichthys, Stichceus, Cenironotus, 

 Apodichihys ; Psychrolutes ; Auliscops. 



EmMotocidoB. 



Gadus. Hippoglossus, Pseitichihys, Citharichihys, Para- 

 lichthys, Pleuronectes, Parophrys. 



Osmerus, Thaleichthys, Hypomesus ; Ungraulis, Clupea. 



Syngnaihus. 



III. — The Equatoeial Zone. 



As we approach the Tropic from the north, the tribes 

 characteristic of the Arctic and Temperate zones become 

 scarcer, and disappear altogether : to be replaced by the 

 greater variety of Tropical types. Of Chondropterygians, the 

 Ghimmridm, Spinacidce, Mmtelus, and Baja, do not pass the 



