. Text-book of zoology for junior students. Zoology. 100 INVEUTJililfATE ANIJIALS. the test is \'croil with numerous tubercles of tliffereut sizes, which carry lunger or shorter sjiiues (tij,'. Gl, E). The K]>ines are jointed to the tuljercle by a sort of " Ijall-anil-socket" or " universal" joint, and they are com2)letely under the control of the animal, so as to be used both iu locomotion and apparently as defensive weapons. In most of our British species tlie spines are short, but in many tropical forms they attain a very great length. Besides the spines, the outer
. Text-book of zoology for junior students. Zoology. 100 INVEUTJililfATE ANIJIALS. the test is \'croil with numerous tubercles of tliffereut sizes, which carry lunger or shorter sjiiues (tij,'. Gl, E). The K]>ines are jointed to the tuljercle by a sort of " Ijall-anil-socket" or " universal" joint, and they are com2)letely under the control of the animal, so as to be used both iu locomotion and apparently as defensive weapons. In most of our British species tlie spines are short, but in many tropical forms they attain a very great length. Besides the spines, the outer. Fig. 61.—Morphc'o^' of Ecliinriidea. .\, Tnmi^' .siiecimen of .^troiujylocenirottis Drb- taclii^nsis, viewed frnm alii'\p ; B, Siiinll pniticui nf 1!r' ti^st nf the sntne magnified: C, KiiiiiTiiit of tlie test of sjihirnf, iiiauniified; D, l_'l!/p>'.( siih'lrprf^^us, viewi'il .-[liove, sliowiie,' (lie anilinliiriM ; E, S]iiiie of I'omriitirris pvr- p,tnil<i; K, I'l-iliC'U.'iria of r„.n-,i„n'iislis lirnhix, e «. areas; / i Inter- . aivas ; .Mieiiilal plate; ,:(]cular ].late ; m tnliercle ; p ;^ tie- amis. (Im:,'s. .\, B, auit D iue after A. Agassiz.) surface of the test is furnished M'ilh curious little bodies called "pedicellariie " (lig. (il, F), whicli wei'e lo]ig believed to be j)arasitic. They consist fif two or tliree blades mounted u]ion a flexible .stalk, ;ind const;iii(ly employed in |iiiig (o'^'etlier like the beak of a bird. 'J'heV <iia'Ui' in ]u:iuy either Et'hiinulcnii'if't^ ;ind their use is obsciu'e. Tjoroiiiution is eH'crted iu tile S";i-uI'ohills 1)\- ;i i-iii'ious system of rii;itt;ietil(.' fiilies which are' known ;is the ''andiiil;ici-;d tubes" or " lube-feel," ;iiid w liich are appendages of the w;iler-vascular Please note that these images are extracted from scanned page images that may have
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1885
