FISHES—REGAN. 29 



The supposed relationships of the Nototheniiform families and of the genera of 

 the Boviehthyidae are shown by the following diagram : — 



( 'haenichthyidae Bathydraconidae 



Nototheniidae 



Bovichthys 



Cottoperca 



Pseudaphritis 



Boviehthyidae. 



In summarising the distribution of the Nototheniiform.es the Boviehthyidae, the 

 most generalised family, may be considered first. Pseudaphritis most nearly represents 

 the prototype of the whole group and is the only genus peculiar to the South 

 Temperate Zone ; but the single species also (litters from other fishes of the family in 

 that it is chiefly, or perhaps entirely, fraviatile. It may perhaps be regarded as a 

 relict form, analogous to the Galaxias of New Caledonia, dating from a time when the 

 seas of Australia were colder. The related Cottoperca is marine and is confined to the 

 Magellan District, whilst Bovichthys, which seems to be Cottoperca specialised, is 

 principally South Temperate, but is Subantarctic also in the Antipodes District. 



The remaining families include 22 genera; one (Eleginops) is monotypic and 

 oceurs in the Magellan, Chilean and Argentine Districts; the rest are Antarctic, 

 16 peculiar to the Glacial District, one peculiar to the Kerguelen District, and four 

 found also in the Subantarctic Zone. Of these last, two (Dissostichus, Harpagifer) 

 are monotypic, the third (Champsocephalus) has only two species, and the fourth is the 

 large genus Notothenia, well represented in both Antarctic and Subantarctic Zones. 

 The species of Notothenia form five natural groups: — 



(1) the tessellata group, comprising the first eight species in the list and confined 



to the Magellan District ; these have the interorbital region rather broad, the 

 upper surface of the head except the snout, and its sides except the praeorbital 

 fully scaled. 



(2) the squamifrons group, including only N. squamifrons from Kerguelen and 



N. larseni from Graham Land and South Georgia ; distinguished from 

 the preceding by the narrow interorbital region and the scaly snout and 

 praeorbital. 



(3) the acuta group, including the next five species, all belonging to the Antarctic 



