Propeamussium clancularium (Yokoyama, 1926)
YOKOAMA, M. 1926. Tertiary Mollusca from southern Totomi. Journal of the Faculty of Science, Imperial University of Tokyo [Section II: Geology, Mineralogy, Geography, Seismology], 1 (9): 313-364, pls. 38-41 [p. 358, pl. 41, figs. 7-11]
1926 Pecten clancularius Yokoyama, 1926
M. Yokoyama, 1926, plate 41.
|
«Shell small, thin, somewhat translucent, compressed, orbicular in outline, right and left valves being almost of equal convexity. Right valve: external surface with numerous, regular, concentric, incised lines; internal surface with seven elevated radiating ridges, which before reaching the ventral border terminate with ends somewhat swollen. Left valve: external surface with very fine almost microscopic radiating lines; internal surface not quite clear, but apparently with the radiating ridges like the right valve, though probably not so elevated. Ears somewhat unequal, the anterior of tbe right valve being larger than its posterior, with a shallow byssal notch below.
The shell is very fragile and difficult to detach from the stone, so that the internal ridges are known mostly by their impressions on the stone. However, I was able to secure one of the right valves which shows the inner side. It is shown in fig. 11. Frequent. The largest specimen is 10 millim. in length and height. Fossil occurrence.— Hijikata Beds: Tombé.» MATAJIRO YOKOYAMA, 1926
|