FISHES OF THE GULF OF MAINE 



381 



Figure 206. — Leatherjacket (Oligoplites saurus), Marthas Vineyard. From Jordan and Evermann. Drawing by 



H. L. Todd. 



scales are very small, and imbedded in the skin, 

 which is corrugated with a great number of short, 

 fine, longitudinal ridges, giving it a leathery 

 appearance, hence its common name. 



Color. — Bluish above, silvery below, with yellow 

 fins. 



Size. — The largest are about 12 inches long. 



General range. — Common on both coasts of 

 tropical America; northward to New York and 

 southern Massachusetts (Woods Hole), reaching 

 the southwestern part of the Gulf of Maine as a 

 stray. 



Occurrence in the Gulf of Maine. — The only rec- 

 ord of this southern fish within the Gulf is of one 

 taken in a trap off the outer beach at Chatham, 

 Cape Cod. 



Threadfin Alectis crinitus (Mitchill) 1826 8I 



Jordan and Evermann, 1896-1900, p. 931, as Alectis 

 ciliaris (Bloch 1788). 



Description. — The combination of a head 

 strongly convex in dorsal profile, with the fact that 

 the first few rays of its soft dorsal fin, and of its 

 anal fin also, are extremely long, and threadlike, 

 places the threadfin at a glance among the ca- 

 rangoids of our northeastern coast. On small fish 

 these threadlike rays are considerably longer than 

 trunk and tail combined, but they shorten with 

 age, probably to be entirely lost. The trunk of 

 the threadfin is nearly as high as it is long (to the 

 caudal peduncle), the dorsal profile of its head is 

 strongly convex and it is strongly flattened side- 



" We follow Smith (Copeia. 1938, p. 146) in using tbe name crimtus Mitchill 

 1826, proposed for a specimen taken near Block Island, R. I., rather than 

 ciliaris Bloch 1788 (type locality East Indies), awaiting final decision as to 

 the true relationship between the threadfins of different oceans. 



wise. It has one dorsal fin of 1 stiff ray and about 

 19 soft rays, preceded by 6 short, separate, in- 

 conspicuous spines; the anal has 1 stiff ray and 

 16 soft rays, and is preceded by 2 spines so short 

 that they are likely to be overlooked. Its lateral 

 line is strongly arched over the pectoral; and the 

 rear part armed with a series of bony platelike 

 scales; the tail fin is deeply forked and the ventrals 

 are larger than in most other carangoids. The 

 pectorals are about as long as the head. 



Color. — Upper surface bluish, the sides silvery, 

 with traces of darker bars and blotches that tend 

 to disappear with age; the prolonged parts of the 

 dorsal and anal fins are bluish black; ventral fins 

 mostly black; the fins otherwise more or less 

 yellowish. 



Size. — Specimens with the long threadlike fin 

 rays have been reported up to about 7 inches long, 

 in West Indian and Atlantic United States waters. 

 But it now seems very probable that these are the 

 young of the Cuban Jack (Hynnis cubensis Poey 

 1860). Their transformation consists chiefly in 

 losing the filamentous fin rays; in a decrease 

 in the depth of the body relative to its length; in 

 a very considerable decrease in the relative size of 

 the ventral fins; and in the assumption of a more 

 falcate shape by the pectorals. 



General range.- — The threadfin (or threadfin 

 stage of the Cuban Jack), is known on both coasts 

 of tropical America; it strays northward on the 

 Atlantic coast to southern Massachusetts, and it 

 has been reported once from the Gulf of Maine. 

 The adult Cuban Jack has not been reported north 

 of southern Florida. 82 



93 We have seen one taken at Key West, and there is one from the east 

 coast of Florida in the Museum of Comparative Zoology. 



