PODOBRANCHIA AND EPIPODITES., 167 
the podobranchia is taken by a broad soft membranous 
plate entirely devoid of branchial filaments (ep). Thus, 
in the series of the thoracic limbs, on passing forwards 
from the third maxillipede, we find that though the plan 
of the appendages remains the same; (1) the protopodite 
increases in relative size; (2) the endopodite diminishes ; 
(3) the exopodite increases; (4) the podobranchia finally 
takes the form of a broad membranous plate and loses its 
branchial filaments. 
Writers on descriptive Zoology usually refer to the 
parts ofthe maxillipedes under different names from those 
which are employed here. The protopodite and the endo- 
podite taken together are commonly called the stem of 
the maxillipede, while the exopodite is the palp, and the 
metamorphosed podobranchia, the real nature of which 
is not recognised, is termed the flagellum. 
When the comparison of the maxillipedes with the 
abdominal members, however, had shown the funda- 
mental uniformity of composition of the two, it became 
desirable to invent a nomenclature of the homologous 
parts which should be capable of a general application. 
The names of protopodite, endopodite, exopodite, which 
I have adopted as the equivalents of the “stem” and the 
“‘palp,” were proposed by Milne-Eidwards, who at the 
same time suggested epipodite for the “‘ flagellum.” And 
the lamellar process of the first maxillipede is now very 
generally termed an epipodite ; while the podobranchie, 
which have cxactly the same relations to the following 
