128 ACANTHOPTERYGII 



B. vii, D. 3-6 I ^^'^^, P. 19-21, V. 1/5, A. 0-2 | 16-17, C. 17, Coec. pyl. 12-16, 

 Vert. 10/16. 



Length of head 4-1- to 4^, of pectoril fin 8, of caudal fin 5|, height of body 

 4 to 4i in the total length. Eye — diameter 5 in the length of the head, 

 11 diameters from the end of the snout, and 2 apart. The gi-eatest width of 

 the head equals 3/5 of its length, its height equals its length behind its 

 posterior nostril. Jaws nearly equal in front or the lower slightly projecting, the 

 maxilla reaches to beneath the front edge of the eye. Teeth — villiform in the 

 jaws, in a pyriform band on the vomer, and in a long patch upon the palatines : 

 tongue rough. Fins — free spines, composing first dorsal fin, all short: second 

 dorsal fin highest anteriorly : anal commences below the 10th or 12th dorsal ray, 

 it has generally two free spines anterior to it. Caudal forked. Pectoral as long 

 as the ventral, which reaches two-fifths of the distance to the base of the anal. 

 Scales — small and cycloid. Lateral-line — makes a gradual curve to above the 

 first third of the anal when it is continued direct to the middle of the base of the 

 caudal fin, forming a raised keel in the last portion. Colours — bluish, with five 

 or six dark (in the live fish purplish-green) vertical bands, nari-ower than the 

 ground colour. Fins gray, with three of the body bands continued on to the 

 dorsal, which has also a white upper tip : and two bands on to the anal, which 

 is similarly white tipped. The ends of each caudal lobe white with a dark base. 

 Pectoral with a light outer edge. 



Young, Plate XLV, fig. 2 (3/1), after Liitken. 



These differ considerably from the adult, and have been placed in distinct 

 genera. In Cuv. and Val. they form the genus Nauclern-s, represented as having 

 a continuous first dorsal fin and a spine at the angle of the preopercle. Sir 

 J. Richardson in the Voyage of the Erebus and Terror, plate sxx, fig. 22, 

 represents the very young under the name of X;/sfop]iorus (as pointed out by 

 Liitken). It has spines on the supraorbital edge, at the angle and lower margin 

 of the preopercle, and likewise along the lower edge of the interopercle. In an 

 example I have from the Andamans, 9/10 of an inch in length, there is a strong 

 spine at the angle of the preopercle and two along its lower edge: the others 

 are almost lost. 



Varieties. — A black iorm., Scomlier viijer, Bloch, t. cccsxxvii, has been observed. 



Names. — Pilof-Jisli. a name which it has received from the propensities 

 attributed to it by some authors, denied by others. Le Pilote, French. 



Hahits. — This fish has long been celebrated as the companion and the guide of 

 sharks, as it was formerly said to be of whales, and also the friend, or at least 

 close attendant, on ships while sailing over the ocean. Although some consider 

 the pilot-fish to be the friend of the shark, others have thought such open to 

 suspicion, while Cuvier has even suggested downright enmity or rather treachery 

 in its actions. M. Geoffrey tells how two of these fishes wei'e observed to lead 

 a shark tip to a baited hook which by their importunities they induced him to 

 goi-ge. Or as Cuvier pithily puts it, that this tale if true should occasion them to be 

 termed " deceivers " rather than "pilots." Captain Richards once observed upon a 

 blue shark attended by four pilot-fishes following his vessel in the Mediterranean; 

 a bait was displayed, but the little pilot-fishes pertinaciously came to the front and 

 with their .snouts thrust the baited hook away. All at last swam away together, 

 but suddenly the shark changed its mind, turned and rushed forwards with all 

 speed at the bait, leaving his faithful attendants far behind, and which only 

 arrived as the body of their companion was being hauled up on board, to which 

 one is said to have clung until it was half above water, when it fell off leaving it 

 doubtful if it was not a sucking-fish (see p. 108 ante). Why the shark does not 

 prey on its companions is a mystery. Lacupede thought their agility saved them, 

 and that their flesh is not worth the eating. 



In the ISIaturali.sts' Note-book (1869, p. 255), a writer (J. D. S. W.) mentions 

 " we frequently threw pieces of flesh into the water to them. The pilot-fish first 

 came up and smelt the meat, and then went away and led the shark to it, A^ho 

 always swallowed the whole and left none for his little companions. On a daik 

 night yoit can see the entire shape of the shark in the waiter below, shining all 



