ROUGH MOUND. 



lis; 



close to the correspondinji lobe of tlic other side that 

 an almost continuous nasal valvule is produced, not 

 unlike that of the Hays — the posterior margin of the 

 nostril is also furnished internally in hotli species with 

 a dermal lobe, wliicli in the Nurse Hound, however, is 

 simple and thin, jirojecting like a leaf into the back- 

 ward iiarial groove, Init here develojis into two barbel- 

 like processes, one of them (above the dotted line from 

 Ipi) jutting into the said groove, the otlier (l)elow the 

 dotted line from lj)i) directed backwards and laid witliin 

 the moutli, 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 ot the upper jaw 

 swells towards the corners of the mouth in a labial form. 



As a compensation for the absent nictitating mem- 

 brane these Shai'ks possess the faculty of raising the 

 lower eyelid so high that tlie orbits become shut; and 

 NiLSSON as well as Malm lias described how the Rough 

 Hound can close the pupil by contracting the iris, till 

 the latter leaves open only a narrow longitudinal slit, 

 dilated at eacli end. 



The fins of the Rough Hound are most like those 

 of the Black-mouthed Dog-iish; 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 tins are shorter, 

 the l)ase of the former measuring only about 9 — 10 % 

 of the length of the liody. 



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 

 witli on the west coast of Norway, south of Bergen, 

 and in tlie Cattegat — even in the Sound, between 

 Malino and Helsingborg, one sjiecimen has been taken 

 (LiLL.iEBnRCi). Off Mouiit Kulleii, according to NiLSSON, 

 it is familiar enough to bear a special name {Hdshlrf- 

 vincj); and at Agger, on the west coast of .lutland, it 

 is known, according to Feudeksen, as the Tasluij 

 (Toad Sliark). 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. Fukdeuicksen, 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. Wlien it lives on 

 a clayey bottom, the body has a different gi-ound-colour, 

 darker (grayish or blackish) with still darker spots 

 (Thompson). In its reproduction, tem])erament, and 

 general habits, this species resembles the preceding one. 

 Both liave something of the serpent about them, as 





Fig. 337. Ventral side of a Rougli Hound {Scylliorhiuus canicida), 

 (f, from Messina, 6—10 fthnis., stony bottom, Feb. 5, 1891, C. 

 BOVALLIUS. ' ,, nat. size. The anterior outer lobe (lae) of tlie right 

 nostril is raised to show the anterior inner (/ai), the posterior outer 

 (/jue), and tlie posterior inner (Ipi) lobes. 



they sway their whole body in sinuous movements; 

 and both are gregarious, each species by itself, as tliey 

 chase schooling fishes. To the Herring and Pilchard 

 they are dangerous enemies, and they cause tlie fisher- 

 man trouble by tangling and tearing liis nets. Tlie 

 long-line fishermen too complain of them. In tlie Eng- 



