226 ZOOLOGY. 



are also very variable, in some seasons the returns hardly paying the expense 

 of the expeditions. Some idea of the extent of the trade may be formed 

 from the fact that, in a single year, upwards of 234,000 barrels were taken 

 by Massachusetts fishermen alone. A closely allied, but smaller species, 

 S. grex, or chub-mackerel, is distinguished by a dark spot at the tip of the 

 lower jaw. S. colias, or the Spanish mackerel, is also much esteemed, but 

 rarer than the two preceding. It is distinguished from S. vernalis by the 

 fact that the transverse undulations do not cross the lateral line, as in the 

 latter species. In S. vernalis, also, there is a dusky line beneath the lateral 

 line, and a black spot at the base of the pectoral and ventral fins. Scomber 

 vulgaris, or the common European mackerel, is represented in pi. 83, 

 ßg. 9. The genus Thynnvs, or tunny, is distinguished from Scomber by 

 the presence of a corselet round the thorax, formed by scales larger 

 and coarser than those .of the rest of the body. There is a bony and 

 elevated crest on each side of the tail. The anterior dorsal reaches nearly 

 to the posterior. Numerous finlets behind the dorsal and anal fins. A 

 single row of small pointed teeth in each jaw. The common tunny, 

 Thynnus v^dgaris, is a mackerel of a gigantic size, and famed for the 

 excellence of its flesh, which tastes something like lean pork. Fish of this 

 species are caught in immense numbers in the Mediterranean, and eaten 

 both fresh and salted. The usual method of preserving them for any 

 length of time is to cut them into slices, which are packed away in barrels, 

 with layers of salt interposed. They are generally caught in nets. This 

 species is of rare occurrence out of the Mediterranean, where it is met 

 with in great shoals. But few are recorded as being caught off the United 

 States coast ; one specimen, taken near Cape Anne, weighed 1000 lbs., 

 and was fifteen feet in length. In New England it is known as horse 

 mackerel and albicore. A European specimen is figured in pi. 83, fig. 8, 

 A second species, of much smaller size, is found in the Gulf of Mexico. The 

 bonito is also a species of Thynnus (T.pelamys), differing mainly in several 

 large longitudinal stripes below the lateral line. It is this species, among 

 others, which causes the flying-fish to leave the water in order to escape from 

 its terrible enemy. The flesh is greatly inferior to that of the common tunny. 

 The genus Pelamys differs from the last, in having strong separated and 

 pointed teeth. The principal species, P. sarda, also called bonito, is of rare 

 occurrence in American waters, where it is known as the skip-jack, 

 especially in Massachusetts. Cybium is without a corselet, and has large 

 compressed sharp teeth ; the palatines with short and even teeth. One 

 species, C. maculatum, or spotted mackerel, is of rare occurrence on the 

 American coast. The genus Xiphias, or sword-fish, has a spindle-shaped 

 body, covered with minute scales, a single elongated dorsal fin, ventrals 

 wanting, upper jaw elongated, forming a sword-shaped protuberance ; 

 mouth without teeth. This curious genus, represented by Xiphias gladius, 

 or the well known sword-fish {pi. 81, fig. 13), is generally distributed 

 throughout the Atlantic, being found on both the European and American 

 shores. It attains to a great size, being sometimes fifteen feet in length, 

 and weighing many hundreds of pounds. The flesh, especially of the 

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