The new genus resembles species of the genus Syringammina, in particular the type species Sy. fragilissima. The genera are similar in the general shape and construction of the test, which consists of a framework of bar-like elements, forming a tightlymeshed, often reticulated structure. The main morphological difference between the new genus and Syringammina is the nature of the test wall. In Syringammina, the wall is brittle, with a smooth inner surface, and consists of ‘tightly cemented xenophyae’ (Tendal, 1972). These comprise mainly fine sand grains and small foraminiferan tests in Sy. fragilissima. Shinkaiya, on the other hand, is characterized by a relatively thick wall that is soft rather than brittle, and consists mainly of clay-sized sediment particles.
Genera of family “Clade CX”
The test is constructed by numerous tubes of tightly cemented xenophyae. The tubes are arranged in a radiating manner, single tubes being connected with other tubes by side branches. The xenophyae are restricted to the tube walls, and only granellare and stercomare are found in the interior.