Bd. V: 6) THE FISHES OF THE SWEDISH SOUTH POLAR EXPEDITION. 29 



of head, reaching be) ond origin of anal, with blunt tips. Cauda! truncate. Caudal 

 peduncle a little shorter than deep. Scales thin, ctenoid, comparatively large on 

 posterior part of the body. Upper lateral line with 25 — 30 tubular scales, lower not 

 conspicuously developed.* In a specimen with 25 tubular scales in upper lateral line 

 about 20 more scales can be counted from posterior end of the lateral line to caudal 

 fin. The total number in a longitudinal series of scales above the lateral line might 

 be approximately about 60. 



The length of the three specimens is from 39 to 45 mm. without caudal fin. 



The number of rays in dorsal and anal fins of this fish resemble the correspond- 

 ing ones of N. longipes. The ventral fins appear to be even longer than in the 

 latter species. The general appearance of these two fishes is, however, quite diffe- 

 rent. N. longipes is less compressed and its depth of body is, at least in young 

 specimens, smaller when compared with the total length than in the fish named N. 

 dubia. The latter has also much smaller eyes, the diameter of which is shorter than 

 snout (in N. longipes longer). The scales of the head are much better developed 

 in N. longipes and even in small specimens seen all over the whole interorbital re- 

 gion. This comparison between specimens of similar size proves the diversity of 

 the two fishes mentioned. From N. nicolai the present fish differs through its scaly 

 occiput, and the same character prohibits its referring to N. coriiceps and N. cyaneo- 

 brancha, the two latter also having a much broader and more depressed head of 

 entirely different shape. N. elegans has a narrower interorbital region, and the eyes 

 longer than the snout. N. marionensis has a much narrower interorbital space with 

 better developed scales and less compressed body and head, different number of fin 

 rays etc. N. mizops has a narrower interorbital space, still longer ventrals, deeper 

 caudal peduncle, larger eyes etc. N. siiiia has different number of fin rays, better 

 developed scales on the head, larger ej'es etc. A\ tesselata has much shorter vent- 

 rals, larger eyes, more scaly head etc. 



The differences between the 3 specimens of Notothcnia from Boiler Harbour and 

 other species of Notothenia are thus quite apparent without the necessit}- of extending the 

 comparison to the species with extremely broad or extremely narrow interorbital space. 



A few comparative measurements of N. dubia are recorded below. 



Total length without caudal in mm 43,5 



Length of head in % of total length without caudal 27,8 



> snout » » .. .1 I. ., > g^. 



Diameter of eye > ? > > » > » 7^1 



Interorbital width »»>> > » » 14,9 



Length of ventral fin » ». 1 > > 23,9 



Depth of caudal peduncle s » 1 » » > » 7^4 



* The line with a corresponding situation in the figure (fig. 9 PI. Ill) represents only the very con- 

 spicuous limit between the upper and lower portions of the lateral muscles. 



