37 



SPINY-FINNED GROUP. 



the teeth; and the two short ridges on each side of the caudal fin. Although 

 there are but 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 

 (8. vernalis) 1 has no air-bladder, while the southern mackerel (8. pneumatophorus) 

 takes its name from the presence of that organ, which likewise exists in the 

 Spanish mackerel (8. collets). 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 Ibs. 

 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 

 which the name tunny (Thynnus 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 

 thynnus for the tunny. 



Tunnies. 



