. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE ECHINODERMA. 543 «tem cirri are entirely wanting except near the point of fixa- The uppermost plate of the stem is usually regarded as fonniug the apex of the calyx and is termed the ceTrlTLd Above this comes in most recent forms a series of usuaHy fi e sometimes three) interradial plates, the basals (FigS f bu one genus naun^nfocrinus, there occurs between th ecen tiodorsal and basal plates a series of five radial plates which are termed the parabasals or under- l
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE ECHINODERMA. 543 «tem cirri are entirely wanting except near the point of fixa- The uppermost plate of the stem is usually regarded as fonniug the apex of the calyx and is termed the ceTrlTLd Above this comes in most recent forms a series of usuaHy fi e sometimes three) interradial plates, the basals (FigS f bu one genus naun^nfocrinus, there occurs between th ecen tiodorsal and basal plates a series of five radial plates which are termed the parabasals or under- l)Hsals, and which have also been found to occur in the embryo of Antexlon, later on fusiug with the centrodorsal. Succeeding the ba- sals are from two to seven circles <^f radials (r), each circle being also composed of five plates termed - ^j^^ tlio first, second, third, etc., radials Fm. ,'„k. apica. system according to their succession "^ Melocrinm (fossil) (fro,,, counting from the centrodorsal. "' In Aniedon and some of its allies tiie number of cycles of radials s<^en from the exterior is one .sliv he second: and furthermore in the same forms the b sals have also been pushed, as it were, within the calvx lave fused to iorm a single plate, the so-called . MI g. 251, 7?o,v). winch rests upon the centrod<.rsal. par- uly dosing a cavity in that plate. The terminal sually present two articuL-tting facets in their distal sur- 'es and are generally know., as the r,.r; (Fi. 2r,0 a) -cc he arms articulate with them. In the ^.n^TljJ: ... betw^^n each pair of first radials an interradial plate -n s. a condition frecpiently found in fossil genera ii), but sua^y wanting in recent forms. These various plates which <;;•. the apical system are united by sutures, the edce« ^. .lie various senes of plates coming into contact, that a *H'"Hupportisationlod for the arms BnoNN), a - Hxillary plates. * ~ ))!isa! plates
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1896
