398 



&rnuttrn nf Natural ^ 



vations on this subject, which were made 

 when speaking of the Herring, are equally 

 applicable here ; and, to the able zoologist 

 (Mr. Yarrell) whom on that occasion we 

 quoted, we are now further indebted for the 

 following sensible arguments in support of 

 this theory. He says, " It does not appear 

 to have been sufficiently considered, that, 

 inhabiting a medium which varied but little 

 either in its temperature or productions, 

 locally, fishes are removed beyond the in- 

 fluence of the two principal causes which 

 make a temporary change of situation ne- 

 cessary. Independently of the difficulty of 

 tracing the course pursued through so vast an 

 expanse of water, the order of the appear- 

 ance of the fish at different places on the 

 shores of the temperate and southern parts 

 of Europe is the reverse of that which, ac- 

 I cording to their theory, ought to have hap- 

 I pened. It is known that this fish is now 

 taken, even on some parts of our own coast, 

 I in every month of the year. It is probable 

 that the Mackerel inhabits almost the whole 

 of the European seas ; and the law of nature 

 which obliges them and many others to visit 

 the shallower water of the shores at a par- 

 ticular season, appears to be one of those 

 wise and bountiful provisions of the Creator, 

 by which not only is the species perpetuated 

 with the greatest certainty, but a large por- 

 tion of the parent animals are thus brought 

 within the reach of man ; who, but for the 

 action of this law, would be deprived of 

 many of those species most valuable to him 

 as food. For the Mackerel dispersed over 

 the immense surface of the deep, no effective 

 fishery could be carried on : but, approach- 

 ing the shore as they do from all directions, 

 and roving along the coast collected in im- 

 mense shoals, millions are caught, which yet 

 form but a very small portion compared 

 with the myriads that escape." 



The usual length of the Mackerel is about 

 fourteen inches, or varying from twelve to 

 sixteen : but in the northern seas it is occa- 

 sionally found of greater size. Its colour on 

 the upper parts, as far as the lateral line, is 

 a rich, deep blue, accompanied by a varying 

 tingeof green, and marked by numerous black 

 transverse streaks, which in the male are 

 nearly straight, but in the female beautifully 

 undulated : the jaws, gill-covers, and abdo- 

 men are of a bright silvery hue, with a slight 

 varying cast of gold-green along the sides. 

 The scales are small, oval, and transparent ; 

 the pinnules or spurious fins are small, and 

 five in number both above and below : the 

 nose is pointed ; the under jaw the longest ; 

 the teeth are alike in both jaws, curving 

 slightly inward ; and the tail is crescent- 

 shaped. Beautiful as are the colours of the 

 Mackerel when alive, no sooner is it caught 

 than its lustre begins to disappear. It is a 

 voracious feeder, and its growth is rapid ; 

 but it is not the largest fish that are accounted 

 the best for the table. Those taken in May 

 or June are considered superior in flavour 

 to such as are caught either in the spring 

 or autumn. There are various modes of fish- 

 ing for Mackerel ; but the way in which 

 the greatest numbers are taken is by drift- 

 nets. 



MACROTJRA. The name of a very ex- 

 tensive group of crustacous animals, (other- 

 wise called Long-tailed Decapods), including 

 Lobsters, Prawns, Shrimps, &c. At the end 

 of the tail is a sort of fin, expanded laterally, 

 which serves, by its vertical strokes, to pro- 

 pel the animals through the water. 



MACTR A : MACTRAD^E. A genus and 

 family of Molluscous animals of the order 

 Conchifera Dimyaria. Shell oval, transverse, 

 with thin cardinal and lateral teeth ; valves 

 slightly inequilateral, and gaping a little on 

 each side ; bosses protuberant. Animal, foot 

 sharp, oval, and long. The Maetrse live in 

 the sand, and are universally diffused. The 

 genus includes many rare and beautiful 

 species ; though the shells exhibit rather a 

 diversity of form, they are generally more 

 or less triangular. 



MADREPHYLLL3EA. The name given 

 to an extensive group of Zoophytes, forming 

 part of the MADKKPOKES. [See next Art.^ 



MADREPORE. A submarine substance, 

 resembling coral, and_ consisting of carbonate 

 of lime with some animal matter. It is of a 

 white colour, wrinkled on the surface, and 

 full of cavities or cells, inhabited by a small 

 animal, which discharges a liquid from 

 which the stony substance is formed. " Those 

 beautiful rocky masses," observes Mr. Rymer 

 Jones, " for such they appear to the vulgar 



eye, called Madrepores, which, branching 

 into countless varieties of arborescent forms, 

 are abundantly met with in the ocean, and 

 so frequently ornament the cabinets of the 

 curious, are merely fabrics constructed by 

 compound Polyps, and owe their growth to 

 the accumulation of earthy particles de- 

 posited within a fleshy substance that is 

 nourished by countless Polyps, more or less 

 resembling Hydrce, diffused over all its ex- 

 ternal surface. * * * Every one of the 

 branchy stems of the Madrepore is seen, 

 upon a cursory survey, to be covered with 

 multitudes of minute pits or depressions, 

 although these, from the smallness of their 

 size, are scarcely visible to an inattentive 

 observer. Examined with a magnifying 

 glass, however, each of these multitudinous 

 orifices is found to be a cell of beautiful con- 

 struction, equally remarkable for the mathe- 



