TYPE SPECIES. — Leuconia stilifera Schmidt, 1870 by monotypy.
DIAGNOSIS. — Baeriidae in which the cortex is formed by tangential triactines and microdiactines. The choanoskeleton is composed almost exclusively of irregularly scattered giant tetractines, and numerous microdiactines. Both the cortical and atrial surfaces are covered by a dense layer of microdiactines. While in the cortex microdiactines overlay the continuous layer of tangential triactines, they are the sole skeleton of the exhalant aquiferous system.
DESCRIPTION
Like Baeria, Leucopsila has a massive body, with an irregular leuconoid aquiferous system organized around exhalant canals that are distributed in the choanosome in the form of an anastomosing network. The organization of the skeleton is similar in Leucopsila stilifera (Schmidt, 1870) and Baeria johnstoni (Carter, 1871); the major distinction between the two being the replacement of pugioles in the skeleton of the exhalant system of Leucopsila by microdiactines.
Leucopsila is a large sponge that has been reported only from arctic and subarctic waters, both from the Atlantic and Pacific regions (Schmidt 1870; Haeckel 1872; Hôzawa 1919).