ProcAcadNatSciPhila-1887-Pl-VI-Fig-I

Proceedings of the Academy of Natural Sciences of Philadelphia. 1887 Potts on Fresh Water Sponges Pl. VI. Fig I

"Heteromeyenia argyrosperma. Partial section of "chitinous coat" and "crust" of gemmule, showing:—a, the somewhat narrowing "foraminal aperture;" thick "granular crust" charged with–b, "long" and b¹, "short" birotulate spicules. (Pl. XI, fig. i and ii.) The outer rotules of the longer birotulates, when covered by the crust, form conical protuberances as figured. They are, perhaps, more frequently seen naked." --Potts, 1887