. Bulletin of the Geological Society of America. Geology. PLATE ARRANGEMENT IN OLIGOPORUS COREYI. 191 Melonites multijwrus at ambitus. Melonites multq^orus at ven- tral border. Oligoporus danx at ambi- tus. genera, for in the interambulacrum a corresponding progressive develop- ment occurs as well (see classification in table facing page 242). The interambulacrum of Oligoporus coreyi (plate 6, figure 25) terminates ventrally in two plates, 1 and 2, ^ o!. h as shown in both areas of the figure, just as previously seen in Melonites mul- tiporas. As this speci- men is viewed from the inside, the
. Bulletin of the Geological Society of America. Geology. PLATE ARRANGEMENT IN OLIGOPORUS COREYI. 191 Melonites multijwrus at ambitus. Melonites multq^orus at ven- tral border. Oligoporus danx at ambi- tus. genera, for in the interambulacrum a corresponding progressive develop- ment occurs as well (see classification in table facing page 242). The interambulacrum of Oligoporus coreyi (plate 6, figure 25) terminates ventrally in two plates, 1 and 2, ^ o!. h as shown in both areas of the figure, just as previously seen in Melonites mul- tiporas. As this speci- men is viewed from the inside, the left ad- ambulacral column appears on the right side of the figure, et- cetera, and the rela- tive position of the areas appears for the â same reason in inverse order to that shown in Me- lonites multiporus (plate 2, figure 2), which is viewed from the outer or distal side of the corona. This fact must be borne in mind in considering the description of the figure, as otherwise features which are really perfectly normal, accord- ing to the law of growth, would appear abnormal or reversed. Plates numbers 1 and 2 at the ventral border form the basis of the two adam- bulacral columns of pentag- onal plates, as in Melonites. Plate 1 of the right-hand area is mutilated on its ventral aspect, so that it presents a jagged out- line ; but plate 2 is entire on its ventral aspect. This plate has an inclined face leading upward from the ventral to its median portion,. Oligoporus coreyi at ventral bor- der. Palseechinus gigas at ambitus. Rhoechinus elegans at ambitus. Bothriocidarispahleni at ambitus. Figure \.âRelations of the ambulacral Plates. The diagram illustrates the relations of the ambulacral plates at the ambitus or the ventral border and ambitus of the several included genera. Compare with figures in plates and figures 3 and 4, page 234, see also page Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabilit
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