1134 



SCANDINAVIAN' FISHliS. 



openings or about ' . of the length of the head. Tlie 

 cleft of the mouth is horsc-shoed. Its breadth is about 

 eijual to tlie postorbital length of tlie liead. liotli cor- 

 ners of the nioutli are surrounded l)y an impressed 

 fold of skin and are sharply defined, the distance from 

 the tip of the snout to this posterior limit of the li])S 

 varying between about " ,, and "^ , (66 — 77 %) of the 

 length of the head, and tliat from tlie anterioi- margin 

 of the mouth to the same point being about 45 %" of 

 the same length. The teeth are set so unevenly in 3 

 or 4 rows within one another that their number in 

 one of these rows on each side was estimated by Kko- 

 YEii at 7, by Mlllek and Henle at 17, the former 

 having only counted the teeth exactly in a line with 

 one another, omitting those close to (within) these at 

 the intervening spaces. Both the upper and the lower 

 jaAvs are furnished with a thick, but narrow fold (ve- 

 lum) behind the rows of teeth, with lobes answering 

 to the dentition. The tongue is broad and fleshy, but 

 flat. Of the five gill-openings on each side the last 

 t^vo are situated above the base of the ])ectoral fin. 



The t\\'o dorsal fins are of rather similar form, 

 but differ widely in size. Their form may be described 

 as a triangle with the posterior corner raised above the 

 base and stronglj' prolongated. The basal length of 

 the second dorsal fin varies between about 63 and 53 % 

 of that of the first, and the anterior margin of the 

 former measures from about 58 to 48% of that of the 

 latter, which last-mentioned margin increases with age 

 from about 8 to 9';2 % of the length of the bodj-. 

 The distance between the first dorsal fin and the tip 

 of the snout is about Vs (32 — 34 %), that between the 

 second dorsal fin and the same point about ^Z, (63 — 

 67 %), of the length of the body. The anal fin is si- 

 milar to the second dorsal, but somewhat smaller' and 

 situated a little further back". The caudal fin resem- 

 l)les in form that of the Blue Shark, l)ut is shorter, 

 its lengtii from the beginning of the inferior lobe to 

 the extreme tip of the fin decreasing during gro^\■tll 

 fi'om about 24 to 22 'Z, % of the length of the body. 

 The inferior lobe is so deeply forked that it almost 

 seems to consist of two fins, an anteritn-, prolongated 

 forward so as to form a triangular lobe, behind shal- 

 low and of idinost uniform depth, and a posterior, which 



is triangular, and together with the elongated shallow 

 upper caudal lobe, gradually ascending behind, forms 

 the extreme tip of tiie fin. The ]iaired fins are tri- 

 angular. The i)eetorals are of much the same form as 

 the dorsals, but the posterior (inner) corner is only 

 slightly prolongated. The distance bet^v■een them and 

 the tip of the snout measures about 23 — 22 %. their 

 anterior margin about 13 — 15 %, of the lengtii of the 

 body. The ventral fins, which surround the anus, have 

 the form of almost right-angled triangles with conti- 

 guous hypotenuses. These sides, which are about ' ^ 

 greater than the others, measure about 6 — 7 % of the 

 length of the body. The distance from the beginning 

 of the ventral fins to the tip of the snout is about 50 

 — 53 %, to the beginning of the pectoral fins about 

 27—30 %, of the length of the Iwdy. 



The whole skin of the body — witii the exception 

 of triangular pati'hes Itehiiid the cloacal region and 

 the dorsal, the anal, and the pectoral fins — the 

 surface of the fins, and the ca\ity of the mouth, are 

 finely shagreened with small three-spined placoid scales, 

 so small that, ■when stroked from in front, the body 

 is smooth and slippery to the touch, Init in the oppo- 

 site direction feels harsh and rough. 



The external difference of sex is that normal in 

 the Sharks. In the Aoung male represented in our 

 figure the pterjgopodia had not j^et grown beyond the 

 tips of the ventral fins. 



The back, together with the dorsal and caudal fins 

 and the upper surface of the paired fins, is of a steely 

 gray, sometimes with a bronze lustre. The ventral 

 side is \vhite, sometimes with a nacreous lustre, or 

 yellowish. The iris is white, with a narrow ring of 

 cupreous lustre round the black pupil. 



The Tope is knoAvn from the Atlantic, Pacific, and 

 Indian Oceans. In the Atlantic it has been found from 

 the Cape of Good Hope to the Oi'kneys and the neigh- 

 bourhood of Bergen. In the Mediterranean and on the 

 coasts of France, the south of England, and Ireland, it 

 is common. In the North Sea it becomes less frequent 

 of occurrence to the north; but even in the Cattegat 

 it cannot be deseril)ed as rare. North of Bergen it has 

 never been met with; but in Christiania Fjord and on 

 the coast of Bohusliin, as well as in Danish \\aters, it 



" According to Kroyeb soinetimt-s 50. 



' Base about 90—91 % of that of the second dors.il; interior iMart;in about 80 — 80 % of that of tlic- second dorsal. 



' Distance between the second dorsal and the tip of the snout about 98 — 99 ». of that between the anal and the same point. 



