Revised description: The shell consists of a tiny latticed microsphere, a second latticed medullary shell and a rather large third latticed medullary shell (or cortical shell) covered by a thick layer of spongy meshwork that reaches along the peripolar spines on the ring or even beyond the ring. Ring transversally strongly elongated elliptical, with distinct ridge on the inner margin of the ring. Cross-section of the ring therefore triangular with broad base inside. The ring has mostly 1-3 spines in each polar region of the long axis, but may be additionally spined around the whole outer ring margin.
Remarks:Spongosaturninus Campbell and Clark, 1944b is a transitional group to the Saturnalidae Deflandre, 1953. The third medullary shell is so large that it can be also regarded as cortical shell (see Dumitrica, 1985). However, the spongy layer on this shell is always thicker than the distance between the second and third (medullary) shells. In Saturnalis Haeckel, 1881a disappeared this thick outer spongy layer. By this the outer latticed medullary shell was transformed into a latticed cortical shell.
Stratigraphic range:Late Cretaceous. Mesozoic.
Subsequent descriptions:?

Literature cited:- Campbell, A. S. and B. L. Clark (1944b). Radiolaria from Upper Cretaceous of Middle California. Geological Society of America Special Paper 57: 1-61.
- Deflandre, G. (1953). Radiolaires fossiles. Traité de Zoologie. P. P. Grassé. Paris, France, Masson. vol. 1: 389-436.
- Dumitrica, P. (1985). Internal morphology of the Saturnalidae (Radiolaria); systematic and phylogenetic consequences. Revue de Micropaléontologie 28(3): 181-196.
- Haeckel, E. (1881a). Entwurf eines Radiolarien-Systems auf Grund von Studien der Challenger-Radiolarien (Basis for a radiolarian classification from the study of Radiolaria of the Challenger collection). Jenaische Zeitschrift für Naturwissenschaft, 15:418-472.
- Kozur, H. and H. Mostler (1990). Saturnaliacea Deflandre and some other stratigraphically important Radiolaria from the Hettangian of Lenggries/Isar (Bavaria, Northern Calcareous Alps). Geologisch - PaläŠontologische Mitteilungen Innsbrück 17: 179-248.