No. 413.] THE METATHORACIC PTERYGODA. 359 
other basis. To one of these I have already called attention 
(Walton, 1900), notably the formation of the coxa in Chilopoda 
and Hexapoda from two fused pieces to which I have Appues 
the name “ coxa genuina " and 
* meron." 
I have adopted the name v^ 
* pterygodum ” 1 for the pres- 
ent in preference to others 
which have been suggested 
for the mesothoracic piece 
(tegula, parapteron, squamula, 
etc.), since it has priority over 
terms otherwise acceptable, 
and according to our present Fic. 3.—Hydrophilus seiner, Left lat- 
: : era sil yardon of metathorax. x 8. a genuina 
knowledge better indicates the between ante-coxal piece Ae 1 meron. Oe 
function of the part. The term kir as in Fig. n pimeror 
uniet 
“parapteron,” which Comstock 
and Needham (98), following Newport (39), have used in 
reference to the mesothoracic pterygodum, appears inap- 
propriate, for the reason that Audouin (24) first used it 
to indicate a supposed sclerite on the anterior margin of 
the mesothoracic episterna in Dy- 
tiscus circumflexus, the part in ques- 
tion being merely an articulative 
process. Several years later, in a 
» note to a translation of a paper by 
MacLeay (32), Audouin stated his 
belief that the piece in the Hymenop- 
tera termed squamula by MacLeay 
was homologous to the parapteron 
- which he himself had described. 
8 This supposition was not only incor- 
- rect but was subsequent to the ter- 
minology adopted by Latreille. 
The value of the patagium on the prothorax has been more 
or less discussed, but until we know more concerning its devel- 
opment it is impossible fully to decide whether it is equivalent 
1 (gr. mreovydóss (mrepv'yoeiófjs = mrépvyos [wing] + eldos [form]. 
r references as in Fig. 1 
