. The museum of natural history, with introductory essay on the natural history of the primeval world : being a popular account of the structure, habits, and classification of the various departments of the animal kingdom, quadrupeds, birds, reptiles, fishes, shells, and insects, including the insects destructive to agriculture . -Cetacea. 195 themselves in various directions. Often liave we gazedupon tliis rete mirabile, as it is called, with astonishment;and although it has been figured by several autliors, andespecially by Breschet, from whose memoir the an-nexed cut is give
. The museum of natural history, with introductory essay on the natural history of the primeval world : being a popular account of the structure, habits, and classification of the various departments of the animal kingdom, quadrupeds, birds, reptiles, fishes, shells, and insects, including the insects destructive to agriculture . -Cetacea. 195 themselves in various directions. Often liave we gazedupon tliis rete mirabile, as it is called, with astonishment;and although it has been figured by several autliors, andespecially by Breschet, from whose memoir the an-nexed cut is given, none of these representationsfully portray the singularly complicated appearanceproduced by these vascular tortuosities (fig. 77). Thisstructure was iirst acciuately described and explainedby tiie celebrated John Hunter, who observes that the intercostal arteries divide into a vast number ofbranches, which nm in a seipentine course betweert tiiepleura, ribs, and their muscles, making a thick substance,somewhat similar to the spermatic artery in the vessels everjwhere lining the sides of the thorax,pass in between the ribs near their articulation, and alsobehind the ligamentous attachment of the ribs, andanastomose with each otlier. The medulla spinalis issurrounded with a network of arteries in the same man-. Intercostal arterial plexus or rete mirabile of the Porpoise(PhocEena communisj. ner, more especially where it comes out irom the brain,while a thick substance is formed by their ramifica-tions and convolutions; and these vessels most probablyanastomose with those of the thorax. The subclavianartery in the Piked whale, before it passes over thefirst rib, sends down into the chest arteries wliich assistin forming the plexus on the inside of the ribs. I amnot cei-tain but the internal mammary arteries contri-bute to form the anterior part of this plexus. Themotion of the blood in such cases must be very also adds:— The descending aorta sends off thein
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