Notes on Luvarus imperialis Raf., a fish new to:the fauna of Norway. 13 
Taking into consideration all the various circumstances re- 
garding Luvarus, its great horizontal distribution, the fact that 
it has only seldom been stranded on or captured near the coasts, 
its powerful tail fin, the shape of its body with its terminal 
mouth, — all point to pelagic habits, not to those of a bottom or 
littoral fish; its colour places it in that group of pelagic fish, 
which live in the upper layers of the water (as far down as 300 
meters), the absence of teeth suggests plankton nourishment, the 
long intestine points to food which digests slowly. 
The similarity of the digestive canal of Luvarus to that of 
the vegetable feeders, seems to me, in all probability, to point to 
salpae as its chief food, the only group among the makro-plankton 
organisms which from a physiological point of view may be termed 
vegetable matter.*) In the Tunicata *) the principal substance in 
the outer covering — the tunic — chiefly consists (up to 65 per 
cent of its weight) of the so-called tunicine, a substance, which 
both in its composition and when chemically tested, is closely allied 
to cellulose. In the salpae, the tunic (Tunica externa, Testa) 
composes the greater part of the animal. 
As before mentioned, the contents of the intestine was a liquid 
mass of only one kind; after treatment in a solution of formaldehyd | 
this perhaps assumed a somewhat more lumpy, curd-like appearance. 
Under the microscope no distinct pieces, which might be remains of 
crustaceans, plant fibres or the like, could be discovered, altogether 
no other shaped particles were apparent than nuclei, but of these 
there were large quantities (unstained objects and stained with he- 
have been examined, and have been found to consist of a reddish greasy 
mass of a crustacean nature, which was so far digested as to render it 
impossible to define it more exactly than by calling it plankton crustaceans. 
(Collett 1905). 
1) The arrangement of the gill-rakers and the pharyngeal dentition 
(p. 9), seems to me, to give further evidence in support of the view here 
set forth. The way that the gill-rakers are arranged do not indicate that 
their principal object is the straining of small animals from the water. 
The slender but sharp pharyngeal teeth may well be ascribed to a function 
of lacerating such soft bodies as the salpae are, being, however, too weak for 
inflicting more solid material; the specimen here treated had, as mentioned 
p. 10, accidentally swallowed a leaf of grass-wrack, but this showed no 
traces from having passed the pharyngeal teeth. 
*) W. Biedermann. Physiologie der Stiitz- und Skelettsubstanzen 
VIII. Der Mantel der Tunicaten. In A. Winterstein: Handbuch der 
vergieichenden Physiologie. Bd. 3. Theil I, p. 912. Jena 1914. 
