PLATE XV
1, 2, 3, 4, 5, 6, 7. Various curious forms of three winged Astrommas (?) Stephanastrum , or some allied shapes. Fig. 3 has a partial representative in Ehrenberg's Hymeniastrum Pythagoræ, Mik. Pl . XXXVI, fig. 31. In fig. 1 the three arms appear to be hollow tubes of a sort of honeycomb: the extreme measurement, .0211 . The very remarkable border or edge to the spongelike webwork , is the nearest approach I have ever seen to the Rhombic Frame (separated from the web) of the " Stephanastrum Rhombus " shewn on Pl . XXXVI of Mikrogeologie, fig. 33 , and copied into so many works 8. A delicately ornamented spicule (? ) with still a small portion of web adhering to it. All these objects are from Mr. Browne's slides.
