. Birds of other lands, reptiles, fishes, jointed animals and lower forms; . Fhm b) U^. Sa-LilU-Ktnt, COMMON OR SHORT-SPINEDSEA-URCHIN TJiii spfciei is UieJ for food in Italy and other Continental coi STAR-FISHES, SEA-URCHINS, ETC, 349 on a definitely sjmmetrical pattern with minute perforations, such perforations being mostdistinctly visible on the inner surface of the shell. These minute punctures are theapertures through which in life the delicate tubular locomotive organs, or so-called feet,are thrust out and retracted. The majority of these tubular organs terminate in a circularsuc
. Birds of other lands, reptiles, fishes, jointed animals and lower forms; . Fhm b) U^. Sa-LilU-Ktnt, COMMON OR SHORT-SPINEDSEA-URCHIN TJiii spfciei is UieJ for food in Italy and other Continental coi STAR-FISHES, SEA-URCHINS, ETC, 349 on a definitely sjmmetrical pattern with minute perforations, such perforations being mostdistinctly visible on the inner surface of the shell. These minute punctures are theapertures through which in life the delicate tubular locomotive organs, or so-called feet,are thrust out and retracted. The majority of these tubular organs terminate in a circularsucking-disk, wherewith, collectiveh-, the urchin is able to adhere to and travel o\er thesurface of the smoothest rock, or even up the glass walls of an aquarium. In the emptybeach-gathered urchin-shell a circular hole may be observed at the two opposite poles, theone in the centre of the lower and Hatter surface being the larger of the two. It is withinthis lower and larger one that the mouth, with its complex apparatus of teeth, is _ . .*.. LONG-SPINED SEA-URCHI\S TAf neeiHe-like of theu se-a-urcfiins an oier a foot in length. Acres of these creatures may he sometimes seer, on tidally exposedareas of the ^hteensland Great Barrier Reefy ivhere this photograph luas taken The membranous disk \\hich co\-crs the upper and smaller circular aperture in the livinganimal is perforated centrall}- b\- the \ent, and around it are grouped the eye-spots and sundryexcretory apertures. A noteworth)- feature associated with the greater portion of the structural details of thesea-urchin which have been enumerated is the dominance of the number five in the constituentelements. It is found, for instance, that the perforated areas through which the tube-feet areprotruded form, as with the petals and other elements of many flowers, five symmetricallycorresponding segments. The dental apparatus comprises five equivalent tooth-like structures,and there are five eye-spots and five e
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Keywords: ., bookcentury1900, bookdecad, booksubjectfishes, booksubjectzoology
