. Echinoderms of Connecticut. Echinodermata. No. 19.] ECHINODERMS OF CONNECTICUT. 93 here surround a single central plate, however, instead of the intestinal opening. The ambulacral areas are plainly marked on the aboral sur- face of both species by the rows of respiratory tube-feet which are arranged symmetrically about the central plate. The figure thus formed has the general shape of a five-petaled flower (Plates XXVII and XXVIII), and the two groups of each ambu- lacral area are together called a " ; The petals are even more clearly indicated by the rows of double pores on
. Echinoderms of Connecticut. Echinodermata. No. 19.] ECHINODERMS OF CONNECTICUT. 93 here surround a single central plate, however, instead of the intestinal opening. The ambulacral areas are plainly marked on the aboral sur- face of both species by the rows of respiratory tube-feet which are arranged symmetrically about the central plate. The figure thus formed has the general shape of a five-petaled flower (Plates XXVII and XXVIII), and the two groups of each ambu- lacral area are together called a " ; The petals are even more clearly indicated by the rows of double pores on the surface of the disk after the removal of the spines (Fig. 14).. inttr. Fig. 14. Echinarachnius parma. Outline of plates on aboral surface; amh, ambulacral areas; inter, interambulacral areas; a, position of intestinal opening. The four genital pores are shown near the center of the disk. In contrast with the large spines of our regular sea-urchins, the disk-urchins are clothed everywhere with minute, slender, brownish or purplish spines, those on the upper surface being cov- ered with cilia, which cause currents of water to pass continually â over the respiratory tube-feet. The tube-feet in the clypeastroids are specialized either for respiration or locomotion. Those serving the latter function are scattered all over the upper surface in the interambulacral areas as well as in the ordinary position in the ambulacral areas. On the ventral surface they occur along definite grooves in the am- bulacral areas, with branches extending into the interambulacral 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 Coe, Wesley Roswell, 1869-. Hartford, Printed for the State Geological and Natural History Survey
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