No. 413.] THE METATHORACIC PTERYGODA. 361 
exist in front of the patagia which then have the value of 
wings. 
Another interesting question in this connection is the 
homology of the elytra of Coleoptera, for again further inves- 
' tigation must be awaited before a logical conclusion can be 
reached. The tracheation of the elytra, to which attention 
has been called by Comstock and Needham (98), is not con- 
clusive evidence that they are specialized wings, for in connec- 
tion with the view I have here advocated this would be 
expected if they were homologous with the mesothoracic 
pterygoda of the Lepidoptera, and the suppressed wing was 
represented by the alulet so noticeable under the Elytra in 
Hydrophilus, etc. 
From the preceding facts, to which I have called attention, 
it appears necessary to consider that the typical thoracic seg- 
ment (Fig. 5) possesses the components of both pterygodum 
and wing, the former joined to the dorsal margin of the epi- 
sternum, the latter articulated with the dorsal margin of the 
epimeron, while furthermore the morphological position of 
the pterygodum in respect to the wing indicates that it may 
have an important bearing in elucidating the metamerism of 
the antennate arthropods. 
ANATOMICAL LABORATORY, BROWN UNIVERSITY. 
BIBLIOGRAPHY. 
?4 Aupourn, V. Recherches anatomiques sur le thorax des animaux 
articules et celui des insectes hexapodes en particular. Ann. Sci. 
Nat. Zool. Tome i 1, p. 416. 
'86 CHOLODKOWsKY. Zur Morphologie der Insectenflügel. Zoo. dus. 
Bd. ix, p. 
'87 CuoLopxowexy. Ueber die eee bei den Lepidop- 
teren. Zool. Anz. Bad. x, p. 
95 Comstock, J.H. Manual for de do of Insects. 
98 Comstock AND NEEDHAM. The Wings of Insects. Amer. Nat. 
Vol. xxxii, p. 561. 
