. The North American Crinoidea camerata [microform]. Crinoidea, Fossil; Crinoïdes fossiles. 1 s 1)1 'â i 644 THE CRINOIDEA CAMERATA OF NORTH Dorsal cup. A'ciitrul ilisk. b. basnls. R. I'lidials. I. post Ills. ir. iiitcrmiliiils (in part intcTl)racliinl, in part iiitorambiilacriil). ut. iiitcrainlmlacrals of llie regular sides iiitcrambiilacrnls of aual side. u. orals >â />â covering plates. i I Bcmarh.âlhe Platycriiiicloe are the typical family of a sub-group which is distiuguiisiiod from all other i' of the Camerata by having the brach- ials anil intor


. The North American Crinoidea camerata [microform]. Crinoidea, Fossil; Crinoïdes fossiles. 1 s 1)1 'â i 644 THE CRINOIDEA CAMERATA OF NORTH Dorsal cup. A'ciitrul ilisk. b. basnls. R. I'lidials. I. post Ills. ir. iiitcrmiliiils (in part intcTl)racliinl, in part iiitorambiilacriil). ut. iiitcrainlmlacrals of llie regular sides iiitcrambiilacrnls of aual side. u. orals >â />â covering plates. i I Bcmarh.âlhe Platycriiiicloe are the typical family of a sub-group which is distiuguiisiiod from all other i' of the Camerata by having the brach- ials anil intorbrachials only slightly represented in the dorsal cup. The lower brachials, although incorporated into the calyx, belong in part to tlie cup and in part to the disk, and have more or ;s the form of free arm plates. From tliis we conclude that the Platycrinida; represent phylogenct- ically a less developed stage of the Camerate Crinoid, in which the lower arm plates remained in an immature condition, their small size giving rise to the interposition of three plates to fill up the interradial space in the first row, instead of the usual single one. The lower interradials, therefore, are for tlie mJtst part neither strictly interbrachial nor interambulacral, but may be considered as belonging to both. Tliis is not invariably the case, however. In a remarkable undescribed species of Plati/crinus from the Mountain lime- stone of England, the costal and the two distichals are connected with those of adjoining rays by five or six heavy plates, which are strictly interbrachial % i. 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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