. Text-book of zoology for junior students. Zoology. 98 INVE]{TEI!I!ATE ANIMALS. sides of the body. In :-M Ecliinodeims thei'e is a water-vascular sj'stem of tubes, which tenued the "aiubulacral system," which generall)' communicates with the exterior, and which in most cases is used in locomotion. An alinientary canal is always present, and is always comjjletely shut oil'from the ^liueral cavity of the body. There are always distinct of rcjiroihiction, which are almost always jilaced in different individualw, .so that the sexes are distinct. The ner- vous system is in th
. Text-book of zoology for junior students. Zoology. 98 INVE]{TEI!I!ATE ANIMALS. sides of the body. In :-M Ecliinodeims thei'e is a water-vascular sj'stem of tubes, which tenued the "aiubulacral system," which generall)' communicates with the exterior, and which in most cases is used in locomotion. An alinientary canal is always present, and is always comjjletely shut oil'from the ^liueral cavity of the body. There are always distinct of rcjiroihiction, which are almost always jilaced in different individualw, .so that the sexes are distinct. The ner- vous system is in the form of a ling surrounding the gullet and send- ing branches in a radiating manner to different parts of the body. One of the most characteristic j)oints about the Echinoderms is their mode of development. In most cases, namely, the embryo is a little ov:d body covered all over with cilia ; but in the course of growth the ciiia become restricted to transverse bands or to definite outgi-owths of the body. The enibiyo is now often somewhat coni- ad or pyramidal in shajje, with long prr>jecting processes, and may be sup|iorted by a provisional inteiiial .skeleton (tig. 60). An ali-. Fis- fin.âLan-i of /â -V/in,//,.. (.\rtfr ,T. Miillrr.) .\, A, Front ann.'i wiili tliriv iiitenial skeleton; F, F, Aioi.^ ..f the liioiilli - ; H. roslorioi- : a JlolitJi ; r.' : '' Stninach ; h' IiiirsI iiir ; ./ Ciliati'.i bands ; // Ll>aulct,s ; i; Disc of tlie future Krhinu.^. canal with a distinct iiioiUh and anus is present, and the eriil)r>T) is thus divided into t\\*o bil;iter;i]ly synmletric^al halves, l^liis singular en]b]\o was (^)iigiiialiy , in the case of the Si', ,-is an inili'])cndi'nt ;, uiidi'i' the name of " I'; Tho 'il of tlie finilicr develojinient of the embryo is thol the :wlult iiiiirii;d is ultiin,'it"ly di'Veloprd out of a mass of act
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1885
