facets of our polyhedron: the four ãpolarã rays of Mû¥ller ( a or e ) correspond to two adjacent hexagons and two intermediate pentagons of the figure: and Mû¥llerãs ãtropicalã rays ( b or d ) are those which emanate from the remaining four pentagonal facets, in each half of the figure. In some cases, such as Haeckelãs Phatnaspis cristata (Fig. 233), we have an ellipsoidal body, from which the
Table of Contents
CHAPTER IX ON CONCRETIONS, SPICULES, AND SPICULAR SKELETONS
498