A treatise on zoology . Fig. XL. Cylicocrinus nodosns, to exemplify the simplesttype of Camerate tegmen. 1, from 1. post, radius;2, from above. Ay, anus ; B, basals ; hr, openingfor food-groove and underlying canals; ib, largeinterbrachials (suborals, Jacikel). Other letters asusual. (After Joh. .Aluller, lS5o.) x 2. Fig. XLI. Tegmen of (Ussoerinns arfhriticiis,showing ambulacrals (--(j»6) passingdown arms and over apposed orals(0),and becoming enlarged over peri-stome. Post. O remains as a foldedmadreporite; t, anal tube. Otherletters as usual. (From Brit. ) X 3. Actinocrinidae). Th
A treatise on zoology . Fig. XL. Cylicocrinus nodosns, to exemplify the simplesttype of Camerate tegmen. 1, from 1. post, radius;2, from above. Ay, anus ; B, basals ; hr, openingfor food-groove and underlying canals; ib, largeinterbrachials (suborals, Jacikel). Other letters asusual. (After Joh. .Aluller, lS5o.) x 2. Fig. XLI. Tegmen of (Ussoerinns arfhriticiis,showing ambulacrals (--(j»6) passingdown arms and over apposed orals(0),and becoming enlarged over peri-stome. Post. O remains as a foldedmadreporite; t, anal tube. Otherletters as usual. (From Brit. ) X 3. Actinocrinidae). These two facts suggest that the proximal dome-plates of Camerata, regarded as orals by Wachsmuth Sc Springer,and so quoted under head (3), may after all be modified ambulacrals. 126 THE CRINOIDEA. The most conflicting \-iews have been held from time to timeby the same and by different writers as to the homologies of theseplates. That here put forward agrees in the main with Xeiimayrs(1889), but is based on facts not accessible to him. Wachsmuth A: Springer (1897) deny the homology of thed ^^^^^K deltoids in Eublastoidea, Hf/lfOcrinus, and Cya-thocrinidae, with the orals in Haphxrinus andAntedon ; the plates here regarded as enlargedambulacrals (^.7. in Eublastoidea, Cyatho-crinidae, Fig. XLJII., Croialocrinus) are taken^g^^ -r-~^^jr^ by them to be orals, and they imagine thatthey undergo resorption, fission, and otherFig. xlii. changes, stating that they are relatively larger Tegmen of MtgiaoennMs in young specimens. As to the origin and.!^M*!r!^.ut«s, *^ (Afur homologies of the large interradial plates in:h A Springer, in^dunata (here called A or O), those authorsare gradual sinking of the ambulacra and their covering-platesbelow not only the orals but other teg
Size: 1617px × 1545px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
