. Beginners' Zoology . Fig. 54. —Limy Platesin portion of a ray. Fig, 55. — Starfish (showingMadreporite). bilateral symmetry ? The skeleton consists of limy plates embedded in the tough skin (Fig. 54). Is the J-^///rough or smooth ? Hard or soft? Are the projections (or spines) in the skin long or short? The skin ishardened by thelimy plates, ex-cept around themouth, which isat the centre of the lower side and surrounded by a mem-brane. Which is rougher, the mouth side,(^r«/side) or theopposite {^aboral%\d.€)>Which side is more nearly flat ? Thevent is at or near the centre of thedisk on t
. Beginners' Zoology . Fig. 54. —Limy Platesin portion of a ray. Fig, 55. — Starfish (showingMadreporite). bilateral symmetry ? The skeleton consists of limy plates embedded in the tough skin (Fig. 54). Is the J-^///rough or smooth ? Hard or soft? Are the projections (or spines) in the skin long or short? The skin ishardened by thelimy plates, ex-cept around themouth, which isat the centre of the lower side and surrounded by a mem-brane. Which is rougher, the mouth side,(^r«/side) or theopposite {^aboral%\d.€)>Which side is more nearly flat ? Thevent is at or near the centre of thedisk on the aboral surface. It is usually very small and sometimes absent. Why a vent is not of much use will be understood after learning how the starfish takes organ peculiar to animals of this branch, and called the madreporicplate, or madreporite, is found on the aboral surface between the bases of two rays (Fig. 55). It is wartlike, and usually white or red. This plate is a sieve ; the small openings keep ou
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Keywords: ., bookcentury1900, bookdecade1920, bookidbeginnerszoo, bookyear1922
