1130 
SCANDINAVIAN FISHES. 
high, these Sharks are never seen, presumably because 
they are sluggish swimmers and cannot keep up with 
the vessel. In all their actions they greatly resemble 
a hungry dog or a wolf prowling in quest of food; 
hence the names of chien de mer, grand chien bleu , etc., 
which are conferred upon them in several languages. 
Most frequently these Sharks are attended by a little 
fish known among seamen as the Pilot ( Naucrates due- 
tor, see above p. 82, note d). This fish, which is about 
a foot long, presents a handsome appearance, being 
silvery blue with broad transverse bands of dark blue. 
Seafaring folk in general suppose that it guides the 
Shark to the prey in the hope of gaining its share 
thereof, and this belief has been supplemented by all 
kinds of romantic additions. Cuvier, who discerned 
the improbability of these fabulous narratives, was of 
the opinion that the companionship of the Shark and 
the Pilot-fish is merely fortuitous, each of them fol- 
lowing the vessel. But this is not the case. The Pilot- 
fish really attends upon the Shark, but only to feed 
upon its excrements, as a few writers, ancient and mo- 
dern, have correctly stated. I have often had the op- 
portunity on tropical seas of carefully watching Sharks 
accompanied by one or two Pilot-fish, and have always 
made the same observation. The Pilot-fish keeps close 
to the body of the Shark, at the dorsal, pectoral, or 
ventral fins, but now and then quits his post to taste 
some floating object he has espied. Apparently, however, 
he seldom finds anything that tickles his palate, and 
soon returns to the Shark; but the moment the Shark 
passes any excrementitious matter, the Pilot promptly 
and eagerly makes off to secure the prize, and then 
returns to its former station, from which it refuses to 
be enticed for a long while, whereas, when it is hungry, 
it readily swims after any small object thrown into the 
water. I never succeeded in hooking a specimen. In 
the Bay of Bengal I had good opportunity of observing 
that large turtles are also attended by the same kind 
of Pilot-fish; and Sucking-fishes ( Echeneis , see above, 
p. 89, note a) accompany both Sharks and turtles for 
the same reason as the Pilot, but always adhere firmly 
to the body of their host, till they see any morsel of 
food, when they vie with the Pilot-fish in agility, and, 
their errand accomplished, immediately return to attach 
themselves as before.” 
These Sharks are, however, not exclusively salt- 
water fishes. Some of them ascend the great rivers of 
the tropics, even beyond the tidal portion of their 
course. In Scandinavian waters they are strangers; 
but one species has strayed to our coasts. 
THE BLUE SHARK (sw. blahajen). 
G ARCH ARIAS GLAUCUS. 
Plate L, fig. 3. 
Teeth serrated at the margins. Snout more or less conically prolongated to a length of about half that of the 
head. First dorsal fin nearer to the ventral fins than to the pectoral , beginning about half-way between the tip of 
the snout and the base of the caudal fin a . Coloration above of a blackish or grayish blue , underneath white. 
Syn. riav'rog, .ZElian., Anim. Nat., lib. I, cap. XVI, p. 22. 
Galeus glaucus , Rond., De Pise., p. 378; Willughb., Hist. 
Pise., p. 49. Squalus fossula triangnlari in extremo dorso, 
foraminibus nullis ad oculos, Art., Ichth., Gen., p. 69; 
Syn., p. 98. 
Squalus glaucus , Lin., Syst. Nat., ed. X, tom. I, p. 235; 
Bl., Naturg. Fisch. Deutschl., pt. Ill, p. 78, tab. LXXXVI ; 
Rf/tz., Fna Suec. Lin., p. 306; Blvlle {Car char inns'), 
Bull. Sc. Soc. Philom. Paris, 1816, p. 121 (+ C. cceru- 
leus, ibid., efr Fne Franc., I, Poiss., pp. 90 — 92); Guv. 
(subg. Oarcharias), R'egn. Anim., ed. I, tom. II, p. 126; 
Yarr., Brit. Fish., ed. 1, vol. II, p. 381; ed. 2, vol. II, 
p. 498; Bonap., Iconogr. Fna Ital., Pesci, tab. 133, fig. 2; 
Mull., Hle ( Oarcharias , subg. Prionodon), Plagiost., p. 36, 
tab. 11 ( + C. hirundaceus ex Val., p. 37); Couch, Fish. 
Brit. Isl., vol. I, p. 28, tab. VI; Dum., Hist. Nat. Poiss. 
(su. a Buff.), tom. I, p. 353; Barb. Boc., Cap., PeLv. 
Plagiost., p. 17; Gthr, Cat. Brit. Mus ., Fish., vol. VIII, 
p. 364; Mor., Hist. Nat. Poiss., tom. I, p. 329; Mob., 
Hcke, Fisch. Osts., p. 150; Jord., G-ilb. ( Carcharinus ), 
Bull. U. S. Nat. Mus., No. 16, p. 22; Day ( Oarcharias ), 
Fish. Gt. Brit., Irel., vol. II, p. 289, tab. CLII; Coll., 
a The distance between the beginning of the first dorsal fin and the upper transverse notches on the peduncle of the tail is in our - 
young specimen 91 % of that between the same fin and the tip of the snout, which latter distance is equal to that between the anterior 
angle of the pectoral fin and the beginning of the anal fin. In older Blue Sharks the last-mentioned distance is even relatively somewhat 
greater. 
