159 
The Pentacyclidce. 
derived, as we have suggested, from stocks in which a tendency to 
epigyny is displayed— viz., the centrospermal and the parietalian 
VACCINIOIDEAE 
Diagram illustrating the possible origin of the Pentacyclidae. The double 
lines indicate the polyphyletic nature of this origin. 
(see diagram above). The geranial stock, however, shews no such 
tendency, and for this reason we are led to doubt the propriety of 
associating the Vaccinoidete with the descendants of this stock— 
i.e., with the Ericales. The vaccinioidese may, not impossibly, 
represent the progeny of a fourth stock, the rosalian: we shall 
return to this point later. 
We may add finally that, the specialized nature of the habit 
and habitat of many of the Pentacyclidae suggests a prima facie 
presumption that its constituent natural groups represent terminal 
points upon their several lines of evolutionary advance; this pre¬ 
sumption, we shall find, will be justified to a considerable extent in 
the sequel. 
(to be continued). 
