THE METATHORACIC PTERYGODA OF THE 
HEXAPODA AND THEIR RELATION 
TO THE WINGS. 
L. B. WALTON. 
Ow the anterior margin of the prothorax and mesothorax 
of the Lepidoptera are two small sclerites known as the pata- 
gium and tegula, respectively ; while in certain other orders of 
Hexapoda (Hymenoptera, Neuroptera, and Trichoptera) a small 
piece has been found at the base of the 
mesothoracic wing which has been consid- 
ered equivalent to the tegula. Further 
than a few suggestions based on limited 
observations, no attempt has been made 
either to ascertain the value of these pieces 
or to demonstrate the existence of similar 
homodynamous or homologous structures 
in the hexapods. : 
The purpose of the present paper is to 
call attention briefly to the general pres- 
ence of a sclerite on the hexapod meta- 
thorax which seems homodynamous with 
the so-called tegula, to make some sugges- 
tions concerning terminology, and espe- 
cially to point out that the present view 
concerning the metamerism of the anten- 
nate arthropods appears worthy of recon- 
sideration. 
The relation of the tegula, or pterygodum 
as I prefer to term it, to the pieces of the 
mesothorax, which is in many respects 
the most generalized of the three thoracic 
segments in the insects, is shown in Fig. 1. 
y 
F 
herda 
IG. 1. — C. s lignif 
Left lateral portion of mes- 
ora A, pterygo- 
dum (stippled); w, wing; 
eps, episternum ; eft, epi- 
godum extending behind 
the i All 
figures are 
Bearing in mind 
now that the mesothorax and metathorax are equivalent, 
357 
