Knowledge of natural history, revfrom Reason why: natural history, giving reasons for hundreds of interesting facts in connection with zoology; and throwing light upon the peculiar habits and instincts of the various orders of the animal kingdom . 1130. Why have the eggs ofsharks and rays long filamentous proc-esses attached to them? For the purpose of attaching theeggs to sea-weeds, so that they may notbe damaged by being beaten on theshores, nor preyed upon by crustaceousanimals. Each egg consists of a hornycase, filled with a nutritious fluid. Theempty cases are frequently found bythe sea-s
Knowledge of natural history, revfrom Reason why: natural history, giving reasons for hundreds of interesting facts in connection with zoology; and throwing light upon the peculiar habits and instincts of the various orders of the animal kingdom . 1130. Why have the eggs ofsharks and rays long filamentous proc-esses attached to them? For the purpose of attaching theeggs to sea-weeds, so that they may notbe damaged by being beaten on theshores, nor preyed upon by crustaceousanimals. Each egg consists of a hornycase, filled with a nutritious fluid. Theempty cases are frequently found bythe sea-side, and are commonly calledmermaids purses. 1131. Why have the rays, andkindred fishes, long tails armed withspines ? These organs, as well as being usedfor propulsion, are employed as weap-ons of defense, and from the muscularstrength of the fish, are very formidablewhen seized or terrified; its habit is totwist its long and flexible tail roundthe object of attack, and, with the ser-rated spine, tear the surface, laceratingit in an effective KNOWLEDGE OF NATURAL HISTORY. 347 Had I like fish, with fins and gills been made,Then might I in your element have played;With ease have dived beneath yon azure tide.—Fawkes. MISCELLANEOUS. 1132. How is the breathing of fishes conducted?The breathing of fishes takes place by gills. The water, which is impregnated by atmospheric air, is takenin by the mouth, and forced out again by the apertures oneach side of the neck. It is thus made to pass between thegills, which form a set of comb-like vascular fringes, sup-ported upon a system of bones termed the branchical arches,and during this passage the air is absorbed by the bloodof the fish. These fringes are generally four in number on eachside, and are attached by one extremity to an intermediatechain of bones situated opposite the middle of the neck,behind the hyoid bone, while by their opposite extremitythey are joined by ligaments to the under surface of theskull. 1133. Why is
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1916
