37 ° 
SPINY-FINNED GROUP. 
the teeth; and the two short ridges on each side of the caudal fin. Although 
there are hut very few species of mackerel, these have a very wide range; and the 
genus is represented throughout the temperate and tropical seas, with the exception 
of the Atlantic seaboard of Temperate South America. The general coloration 
and form of mackerels are too well known to call for description, and it will 
suffice to mention that of the three European forms the common mackerel 
(S. vernalis) 1 has no air-bladder, while the southern mackerel ( S. pneumatophorus) 
takes its name from the presence of that organ, which likewise exists in the 
Spanish mackerel ( 8. colias ). In a fossil condition this genus occurs in the 
European Eocene and Miocene deposits. Of the common mackerel, which is 
represented in the upper figure of the illustration on p. 364, Yarrell writes that 
NEW ZEALAND GASTROCHISMA. 
“the ordinary length varies from 14 to 16 inches, and their weight is about 2 lbs. 
each; but they are said to attain the length of 20 inches, with a proportionate 
increase in weight. The largest fish are not, however, considered the best for 
table. As an article of food, they are in great request; and those taken in the 
months of May and June are generally considered to be superior in flavour to 
those taken either earlier in the spring or in autumn. To be eaten in perfection, 
this fish should be very fresh.” The enormous takes of mackerel which occasionally 
reward the labours of British fishermen are too well known to need mention. 
Under this general title may be included not only the fish to 
Tunnies. ® J 
which the name tunny {Ihynnus mediterraneus) properly pertains, 
but likewise those commonly designated bonitos and albicores. The genus, which 
comprises some of the largest of all pelagic fishes, differs from the true mackerels 
by the greater number (six to nine) of finlets, by the scales forming a kind of 
1 The author can neither admit the combination Scomber scomber as the title of this fish, nor that of Thynnus 
ihynnus for the tunny. 
