230 



BULLETIN OF THE BUREAU OF FISHERIES 



outline and originates midway from snout to base of caudal. The anal is similar 

 to it in form, but only about half as long (16 or 17 rays) , preceded by two very short 

 spines. In this it resembles the rudderfish, but the first dorsal of the latter is 

 well developed and has 7 instead of 4 spines. The ventrals are situated far forward 

 under the pectorals, and are about as large as the latter. The caudal is large and 

 deeply forked. In the adult the edge of the gill cover is rounded but it bears a 

 spine in young fry. 



Color. — Bluish, transversely barred with 5 to 7 dark bands, two or three of 

 which run up on the dorsal and down on the anal fins. The outer margins of caudal, 

 ventral, and pectoral fins are nearly black. The caudal is white-tipped. 



Size. — Maximum length about 2 feet. 



General range. — A tropical fish of the high seas, rarely straying as far north as 

 Maine. 



Occurrence in the Gulf of Maine. — There are only two definite records for the 

 Gulf of Maine — one near Seguin Island in Maine (1908) and one of a specimen 

 taken in a mackerel net at Provincetown Harbor in October, 1858, the fish having 





Fig. 105.— Pilotfish (Xaucrates ductor) 



probably followed a whale ship that arrived a few days previous. We need merely 

 remark that this is the fish that so commonly attends sharks in tropic seas, either 

 picking up a living from the scraps left by the latter, or feeding on the parasites 

 with which their protectors are infested, and which so often follows sailing vessels. 



86. Rudderfish (Seriola zonata Mit chill) 

 Pilotfish; Shark pilot 

 Jordan and Evermann, 1896-1900, p. 902. 



Description. — The rudderfish much resembles the pilot, but it is relatively 

 deeper bodied (total length three and one-eighth times the depth), so much com- 

 pressed that it is almost as thin as a butterfish (p. 245), and with more pointed 

 nose. The chief distinction, however, is that its first (spinous) dorsal is well de- 

 veloped, and with 7 instead of only 4 spines. Furthermore, there are 37 to 38 

 instead of only 26 to 27 rays in the second dorsal fin and the ventrals are relatively 



