FIG. 10 in A revision of the supraspecific classification of the subclass Calcaronea (Porifera, class Calcarea)

FIG. 10. — Diagram of the leuconoid type of aquiferous system organization, such as observed in many Calcaronea. Instead of a central atrial cavity there is a network of aquiferous exhalant canals that increase in size from the distal regions to the oscula. Abbreviations: cx, cortex; ch, choanoderm; ic, inhalant cavities; ec, exhalant cavities; a, atrium.