Citation: Eucyrtidium delmontense nipponicum Campbell & Clark 1944Rank: sub-speciesDescribed on page(s) : p.56Type specimens: pl.7, figs.19-20Type repository: University of California, Museum of Paleontology, San FranciscoFamily (traditional): TheoperidaeFamily (modern): Eucyrtidiidae
Original Description Description :—Shell slender, nearly spindle-shaped, variable in size and form, with four distinct stricutres which divided into five segments or joints, and with the apical horn ; the first three segments together forming a conical section, the subsequent segments an approximately cylindrical section ; apical horn short, straight, triangular (in the illustrated specimen it is broken off near the base) ; the first segment hemispherical, its length same as long as the lumbar diameter ; the second segment hemispherical, its length about 0.5 length of the third segment, with the curved side, diameter widest at the base ; the third segment the largest and the widest compared to the other segments, spherical, the widest diameter at middle, with the curved side ; fourth segment hemispherical, its length nearly as long as the second segment, but wider that, with curved side ; fifth segment su cylindrical, long (full length is not preserved in the specimen) ; pores of the first segment not present; of the second and the third segments rather large, circular, uniform in size and form, regularly alternately arranged, well spaced, deeply set into the hexagonal meshworks ; of the fourth and the fifth segments smaller than those of the above segments, circular or subcircular, fairly dissimilar in size; the strictures marked by the internal, transverse and distinct septa ; wall thick in general, the thickest part at the third segment, but thickness decreases toward the aperture, and with slightly rough surface. Measurement of the illustrated specimen :—Length of the apical horn, 3A ; of each segment, 22.5, 32.5, 55.0, 30.0, -f 20.0a ; diameter of the shell, maximum, 87.5/.< ; of the pores, 8a. Remarks :—According to the Haeckel's classification, genus Eucyrtidiurn is divided into two subgenera by whether each length of the segment is equal or not. But the legnth of the segments is variable in this collection, and so the writer does not divide the genus Eucyrtidiurn into the two subgenera. This subgenus resmbles E. delomontense Campbell and Clark (1944)* recorded from the Miocene of California and the Western Pacific sediment, but differs from it in that the wall is thicker than the latter, and each length of the segments is unequal. The specimens are similar to E. elongation Stöhr (1880, p. 105, Taf. iv. fig. 10) recorded from the Tertiary rocks of Sicily in that the wall is thick, but the latter has a conical section formed by the upper four segments. It is one of the most widely distributed species in the area. Editors' Notes [Campbell and Clark here list the species with the subgeneric name Eucyrtis and include the subgeneric name in the species name.
Nakaseko, K (1955). Miocene radiolarian fossil assemblage from the southern Toyama Prefecture in Japan. Science Reports, South and North Colleges, Osaka University Osaka. 4: 65-127. gs
Eucyrtidium delmontense nipponicum compiled by the radiolaria@mikrotax project teamviewed: 26-3-2023