1148 
SCANDINAVIAN FISHES. 
mouth, being separated from each other and covered 
within by a sometimes continuous nasal valvule. The 
mouth too of some forms is set very far forward, close 
to the tip of the snout, and fringed with dermal flaps. 
None of these Sharks gives birth, so far as is known, 
to living young. 
Within the Scandinavian fauna three species have 
been observed, belonging to two very similar genera: 
A: Dorsal margin along the beginning of 
the caudal fin armed with spines Pristiurus catulus. 
B: Dorsal margin without special spiny 
armature. 
a: Inner posterior corners of the ven- 
tral fins acutely prolongated, in the 
males coalescent with each other.. Scylliorliinus canicula. 
b: Inner posterior corners of the ven- 
tral fins obtuse, in the males se- 
parated from each other Scylliorliinus stellaris. 
Obs. De Filippi and Verani“ have described from the Mediter- 
ranean a Scyllium acanthonotum, distinguished by a row of spines on 
each side of the back, extending from the middle of the head nearly 
to the end of the first dorsal fin. Of the species, however, they had 
seen only a young individual with vitelline capsule attached. Gun- 
ther * 6 was of the opinion that this young specimen belonged to one 
of the above-mentioned Scylliorhini ; Giglioli c referred it to Pristiu- 
rus. The correct explanation may be left to the future; but it seems 
likely that the spiny armature is a character of youth which dis- 
appears entirely in Scylliorliinus , partially in Pristiurus. 
Genus PRISTIURUS d . 
Nostrils so remote from each other and from the mouth that the distance between their inner angles is perceptibly 
greater than that between either of them and the month , somewhat greater than their length , and about equal to 
the distance between their outer angles and the orbital margin. Distance betiveen the mouth and the tip of the 
snout greater than the postorbital length of the head (to the first branchial aperture ). Anterior part of the upper 
caudal margin (fig. 333, a) armed on each side with a row of retral serrated spines. 
This genus contains only one species, which is 
more nearly approximated by the situation and deli- 
Fig. 333. Egg-capsule of the Black-mouthed Dog-fish ( Pristiurus ca- 
tulus) from the fishing-bank of Jaderen. Nat. size, a, a part of the 
upper edge of the caudal fin in a Black-mouthed Dog-fish 67 cm. long, 
superior aspect, X 5 to show the serrated spines and the scale-rows 
on the dorsal margin between them. 
mitation of the nostrils to the preceding genus than is 
the case with the succeeding one. It also has a more 
finely shagreened skin than Scylliorliinus . In these Sharks, 
as we have seen in numerous Teleosts, e. g. the Gobies 
and Salmons, the scales of the tail are larger than those 
on the anterior part of the trunk. Here we also find 
that the placoid scales of the tail approach more and 
more to the form of the jaw-teeth, least so, however, 
in Pristiurus. Besides the above-mentioned characters 
this genus displays the peculiarity that the tip of the 
tail is bent downwards, whereas in the following genus 
it is straighter. The egg-capsules of Pristiurus (fig. 
333) are distinguished by the absence of horns at the 
extremity directed backwards in the uterus, which end 
is rounded by the incurvature of the corners and in- 
cised at the tip, while the horns at the other end, 
one at each corner, are as short as in the egg-shells 
of the Rays. 
“ Mem. R. Accad. Sc. Torino, ser. 2, tom. XVIII (1859), p. 193, tab., fig. 2. 
6 Cat. Brit. Mus., Fish., vol. VIII, p. 403. 
c Espos. Intern. Pesca Berlin 1880, Sez. Ital., p. 112. 
d Bonap., Fna Ital., Pesci. Established as a subgenus of Scyllium. 
