. Bulletin - United States National Museum. Science. 398 BULLETIN 100, UNITED STATES NATIONAL MUSEUM D'Orbigny, 1852, has described as Lanceopora. Unfortunately the genotype no longer exists at the Paris Museum and as the French author described a round aperture we can not with certainty establish the synonymy. We retain therefore the name of Maplestone. Structure.—The zooecial form is very special; on the interior, it appears lozenge-shaped, but the walls are arched and parallel two by two. This arrangement is absolutely different from that of other bilamellar cheilostomes. As a consequence,
. Bulletin - United States National Museum. Science. 398 BULLETIN 100, UNITED STATES NATIONAL MUSEUM D'Orbigny, 1852, has described as Lanceopora. Unfortunately the genotype no longer exists at the Paris Museum and as the French author described a round aperture we can not with certainty establish the synonymy. We retain therefore the name of Maplestone. Structure.—The zooecial form is very special; on the interior, it appears lozenge-shaped, but the walls are arched and parallel two by two. This arrangement is absolutely different from that of other bilamellar cheilostomes. As a consequence, the aperture undergoes the same deviation; it is not oriented in the apparent linear axis of the zooecium but is oriented in the curved axis of the latter. The mode of gemmation is altogether special. The zooecia of the two axial rows of each segment are arranged normally. They are. Fig. 154.—Genus Hippopodinella Barroso, 1924 A-F. Hippopodinella adpressa Busk, 1854. A. Zooecia without tuberosities X30. B. Zooecia with tuberosities X30. C. A zooecium showing the endo- zooecial ovicell. (A-C. After Hincks, 1880.) D. Operculum, X140. E. Different aspects presented by the marginal cavities when the zooecium is viewed from the dorsal side. F. Ovicelled zooecium decalcified, viewed from the dorsal side; e, embryo; em, mesenchymatous elements; mo, opercular muscles; mp, parietal muscles; mr, retractor muscles. (D-F. After Barroso, 1924.) alternate and engender a distal zooecium and a lateral zooecium. All the other zooecia engender only a lateral zooecium. The general growth is therefore peripheral and the basal lamella (germinale lamella of D'Orbigny) entirely surrounds the segment. In all other cheilostomes this lamella is always terminal. "The zoarium is furnished with a long flexible stem or filament some 6 or 7 cm. long mm. thick, upon the summit of which the zoarium is attached. The point of attachment is at the curved indentation in the center of the lower margi
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