Notes on Luvarus imperialis Raf., a fish new to the fauna of Norway. 27 
Carangidae’) and the Scombridae have small, smooth scales, or are 
entirely without. These two points, the increased number of ite 
vertebrae and diminution of the body’s resistance in the water, 
should be considered in connection with the development of these 
species to fast swimming, pelagic rapacious fish. Luvarus repre- 
sents in these respects a rather primary stage, while, in other re- 
spects, it is a specialized form, for instance in the formation of 
the bony arches, which support the ventral and dorsal contour by 
a close connection of the basal parts of the interhaemal and inter- 
neural spines, a character whose connection with the big, high and 
laterally strongly-compressed body is obvious. The development, 
which Luvarus undergoes, also points to an early divergence from 
the real Scombroids. The young stages (Astrodermus) have a very 
long dorsal and anal fin, the front part of which can be reclined 
in a groove, the reduction of the fins occurs in the cranial region, 
in the Scombroids in the caudal, and this characteristic, the long 
vertical fins of Astrodermus cannot be taken to be a secondary 
developed one of the kind often found in young pelagic stages, 
but more probably points to an earlier stage in this species. With 
regard to the colourings of Astrodermus, it is reasonable to argue 
in the same way, when comparing with those of the adult fish, the 
colourings of the latter being the same in a number of pelagic 
fish-forms belonging to very different groups. In this connection, 
it is interesting that the lateral keel of Luvarus in Astrodermus is 
preceeded by a number (about 4) of sharp, boney spines. The 
presence of caudal keels is a characteristic, which gives a kind 
of resemblance to each other in those species where they occur, 
but systematically speaking, they cannot be considered as of any 
great value, for as a balancing organ it may easily be conceived 
to have arisen in different groups by convergence. In Luvarus the 
lateral keels are particularly powerful, their united breadth is the 
same as that of the body itself at the same place. As already 
mentioned, the structure of the caudal fin of Luvarus is the same 
as that of the typical Scombrijormes, the rays of the caudal fin 
having forked bases and entirely embracing the hypural bone (as 
in Scombridae, Xiphiidae). This feature does not occur in the 
Acanthuridae, and partly for this reason Regan did not con- 
1) Some Carangidae have enlarged scutes on each side of the body or 
of the tail. 
