. The North American Crinoidea camerata [microform]. Crinoidea, Fossil; Crinoïdes fossiles. IIEXACiaXIIKE. 748 Fig. 2i. i. Fi!,'. 20. Ti^. 21, i = b:isiil5; /nce distinguished, already pointed out in the remarks upon that family, b- having a largo anal plate between the two posterior radials, and a hexagonal base, the basals thus six plates, instead of live. The base of the may be composed either of three plates, or only two; but in either case the plates are suli- stantially equal, and form a cup with six salient angles, and cither two or three re-entering angl
. The North American Crinoidea camerata [microform]. Crinoidea, Fossil; Crinoïdes fossiles. IIEXACiaXIIKE. 748 Fig. 2i. i. Fi!,'. 20. Ti^. 21, i = b:isiil5; /nce distinguished, already pointed out in the remarks upon that family, b- having a largo anal plate between the two posterior radials, and a hexagonal base, the basals thus six plates, instead of live. The base of the may be composed either of three plates, or only two; but in either case the plates are suli- stantially equal, and form a cup with six salient angles, and cither two or three re-entering angles at the upper margin. ^Yhen the base is bipar- tite, the suture runs from the anal plate to the anterior radial; but when it is tripartite, the sutures are directed to the anal plate and the right and Id't antero-lateral radials. In either case, therefore, there is always an interbasal suture running to the middle of the anal side, whereas in the Platycrinida> tlie nearest suture to the anal side runs to the middle of the right posterior radial. The genera which we refer to the Tlexacrinidaj were always placed among the Platycrinida> until we separated the two families,* and fm-ther investigation only confirms the validity of their separation. It is based on a fundamental structural modification, for which we find an exact; parallel * Revision, Piirt III., p. 93. 1. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Wachsmuth, Charles, 1829-1896; Springer, Frank, 1848-1927. Cambridge [Mass. ] : Printed for the Museum
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