66 DISCOVERY REPORTS 



NOTOTHENIIDAE 

 Key to the Patagonian genera 



I. Body scaly; gill-membranes forming a fold across the isthmus; opercles normal. 



A. Two or three lateral lines; maxillary usually extending to below eye; pectoral rounded 

 or vertically truncated. 



i. Teeth usually in bands, but sometimes irregularly bi- or triserial with some of the 

 teeth of the outer series enlarged and canine-like; snout not much longer than eye; 

 usually less than ioo scales in a longitudinal series ... ... ... Notothenia. 



2. Teeth in upper jaw biserial, those of the outer row enlarged, spaced, canine-like; 

 a group of stronger canine teeth on each praemaxillary; teeth in lower jaw uniserial, 

 spaced, canine-like; snout much longer than eye; no to 120 scales in a longitudinal 

 series Dissostichus. 



B. One lateral line; maxillary not reaching eye in the adult fish; pectoral very obliquely 

 truncated, the upper rays longest Eleginops. 



II. Body naked; gill-membranes broadly united to isthmus; operculum hooked upwards 

 posteriorly, its upper edge deeply concave; operculum and suboperculum each forming 

 a strong spine Harpagifer. 



Genus Notothenia, Richardson 



Notothenia, Richardson, 1844, Zool. 'Erebus' and 'Terror', Fishes, p. 5; Gunther, i860, Cat. 



Fish., n, p. 260; Regan, 1913, Trans. Roy. Soc. Edinb., xlix, p. 264. Type N. coriiceps, 



Richardson. 

 Macronotothen, Gill, 1862, Proc. Acad. N.S. Philad. (1861), p. 520. Type Notothenia} rossii, 



Richardson. 



The problems raised by the study of the very rich material of this genus obtained by 

 the Discovery Expedition have led me to undertake a new revision of the South 

 American and Falkland Islands species, which amplifies and to some extent modifies 

 those of Regan (1913) and Thompson (1916). This is one of the largest and most 

 characteristic of the genera found in the Patagonian region, and the identification of 

 the species is always a matter of some difficulty. As Regan has shown, the species of 

 this region are very different from those of South Georgia, and, with one or two excep- 

 tions, are peculiar to it. 



Key to the species of the Patagonian region 

 I. Opercles fully scaled. 



A. Upper surface and sides of head scaled, including praeorbital and parts of snout; eye 3 in 

 head (in a specimen of 190 mm.), interorbital width about 9; 42 tubular scales in upper 

 lateral line, which extends to below fourth from last ray of dorsal ... macrophthalma. 



B. Upper surface and sides of head scaled, except snout and praeorbital; eye 3 (young) to 

 6 in head, interorbital width 4 to 8. 



1. 60 to 65 tubular scales in upper lateral line; lower jaw more or less strongly pro- 

 jecting; 9 or 10 rows of scales between the eyes. 



a. 3 lateral lines; jaws without distinct canines ... ... ... ... trigramma. 



b. 2 lateral lines; many of the teeth in the jaws spaced, canine-like... ... canina. 



