ROUGH HOUND. 
1155 
close to the corresponding lobe of the other side that 
an almost continuous nasal valvule is produced, not 
unlike that of the Rays — the posterior margin of the 
nostril is also furnished internally in both species with 
a dermal lobe, which in the Nurse Hound, however, is 
simple and thin, projecting like a leaf into the back- 
ward narial groove, but here develops into two barbel- 
like processes, one of them (above the dotted line from 
Ipi) jutting into the said groove, the other (below the 
dotted line from Ipi) directed backwards and laid within 
the mouth, outside the margin of the upper jaw. The 
lower jaw is furnished in both species, but in the Nurse 
Hound only behind, in the Rough Hound throughout 
the greater part of its length, with a pendent labial 
fold; and the skin on the margin of the upper jaw 
swells towards the corners of the mouth in a labial form. 
As a compensation for the absent nictitating mem- 
brane these Sharks possess the faculty of raising the 
lower eyelid so high that the orbits become shut; and 
Nilsson as well as Malm has described hotv the Rough 
Hound can close the pupil by contracting the iris, till 
the latter leaves open only a narrow longitudinal slit, 
dilated at each end. 
The fins of the Rough Hound are most like those 
of the Black-mouthed Dog-fish; but the dorsals are set 
somewhat further back, the first beginning about half- 
way along the body, the second just- behind the second 
third thereof, and the anal and caudal fins are shorter, 
the base of the former measuring only about 9 — 10 % 
of the length of the body. 
The shagreened skin is fairly alike in both the 
Roussettes, but generally rougher in the Nurse Hound. 
The Rough Hound has about the same geogra- 
phical range as the Nurse Hound, but is somewhat- 
more addicted to northern rovings. On the English 
coast it- is far commoner than the latter, and it is con- 
sidered to be one of the commonest Sharks in British 
waters. In Scandinavia it- is indeed scarce, but not 
among the rarest fishes, for it has repeatedly been met 
with on the west coast of Norway, south of Bergen, 
and in the Cattegat — even in the Sound, between 
Malmo and Helsingborg, one specimen has been taken 
(Lilljeborg). Off Mount Kullen, according to Nilsson, 
it is familiar enough to bear a special name ( Haskdrf - 
vincj ); and at- Agger, on the west- coast- of Jutland, it- 
is known, according to Feddersen, as the Tusliaj 
(Toad Shark). The original of our figure (Plate LI, 
fig. 4) is also from the west coast- of Jutland, and was 
presented to the Royal Museum in November, 1889, 
by Mr. Fredericksen, a Copenhagen merchant-. 
The Rough Hound prefers a sandy bottom with 
its growth of seaweed, as indicated by the reddish co- 
loration the fish generally displays. When it- lives on 
a clayey bottom, the body has a different ground-colour, 
darker (grayish or blackish) with still darker spots 
(Thompson). In its reproduction, temperament, and 
general habits, this species resembles the preceding one. 
Both have something of the serpent about them, as 
lac 
lai \ \ 
Fig. 337. Ventral side of a Rough Hound ( Scylliorhinus canicula), 
cA from Messina, 6 — 10 fthms., stony bottom, Feb. 5, 1891, C. 
Bovallius. V 2 nat. size. The anterior outer lobe ( lae ) of the right 
nostril is raised to show the anterior inner (lai), the posterior outer 
(Ipe), and the posterior inner (Ipi) lobes. 
they stvay their whole body in sinuous movements; 
and both are gregarious, each species by itself, as they 
chase schooling fishes. To the Herring and Pilchard 
they are dangerous enemies, and they cause the fisher- 
man trouble by tangling and tearing his nets. The 
long-line fishermen too complain of them. In the Eng- 
