Notes on Luvarus imperialis Raf., a fish new to the fauna of Norway. 23 
skin; quite the contrary being the case in regard to the scales. 
The decrease in the number of rays in the vertical fins may possibly 
be caused by the foremost rays being laid down in the groove ind 
covered by the skin. 
My specimen of Luvarus, measuring 0.89 m. must be con- 
sidered as half grown, as the maximum size is 1.8 m. (Waite); 
it has in front of the dorsal fin 2, in front of the anal fin 1 ray, 
which is concealed in the skin, but which can still be brought 
into a slanting position (v. page 7). Lowe, according to 
Giinther’) caught a specimen near Madeira, total length 0.89 m., 
of which he writes: — “Close before the dorsal fin is a rather short 
spine seated in a groove, in which, when reclined, it lies quite 
concealed; it is webbed behind in its axil, but perfectly free from 
the dorsal fin’. Lowe would appear to mean that the ray is in 
use. But I cannot share this opinion, the rays are out of use as they 
are overgrown by a layer of skin. The illustration W aite (1902), 
has given of the skeleton of the fully grown Luvarus shows, 
moreover,that in front of the dorsal fin, there is still the proximal 
piece of the interneural spines of that part of the fin which has 
disappeared, whilst the distal parts go into the bony arch, which 
forms the dorsal contour of the body. 
The caudal fin in my two specimens of Astrodermus is a little 
different from that of Luvarus, but there are, at the same time, 
points of resemblance. The lobes of the caudal fin in Astrodermus 
are not so vertical to the longitudinal axis of the body. Its struc- 
ture is, however, the same as that of Luvarus, the base of the rays 
being forked, thus embracing the hypural bone, but the rays from 
the two lobes do not meet in the median line (pl. XLV, Waite) 
as in the fully grown fish, thus giving a more vertical position to 
the lobes. As previously mentioned, the centre rays in the caudal 
fin of Luvarus had become flat, and, when fresh, appeared quite 
cartilaginous. In my Astrodermus specimens this metamorphosis 
has commenced, the rays in the centre, more particularly in the 
larger of the two specimens, being decidedly swollen at the base. 
Without having made a close study of the skeleton, I may mention 
that the ribs in Astrodermus are long and compressed, but have 
not, however, the sabre-like shape of those of Luvarus; the ab- 
dominal cavity is closed in the same way as that of Luvarus. 
1) Giinther, A.: Catalogue of Fishes. Vol. II, p. 414. London 1860. 
