EXTERNAL ANATOMY OF TIIE MOTH. 49 
the neck. So, too, a median section shows that the neck and prothorax 
are really one, Plate VIII, Fig. 2. Two pendulous lobes j? 1 , Fig. 1, Plate 
VIII, project from the upper side of the prothorax, which appear to 
belong to the scutum, but their real homologies are not yet determined 
with certainty. They are constricted arouud their bases, so as to be 
quite movable. Upon the sides, just behind and below them, lies the 
first spiracle, sp l . Below the spiracle are two pieces of elongated shape, 
running down to the insertion of the coxae ; the anterior piece, eps\ is 
the episternum, and meets its fellow on the ventral side, forming a me- 
dian suture between the two coxal articulations, Plate IX, Fig. 1 ; the 
posterior is the homologue of the epimeron of the segments. 
• The mesothorax, Plate VIII, Fig. 1, n, is the largest segment of the 
body. It is longest on the upper side. The principal dorsal piece is 
the big scutum, s 2 , below the lateral edge of which spriugs the front 
wing, tc 1 . Over the base of the wing runs back the large patagium,^, 
which is very much developed; its only connection with the body is in 
front, where it bends over and, as it were, hooks around the front edge 
of the wing. The scutellum, sm 2 , is also prominent and extends for some 
distance over the metathorax. The episternum, eps 3 , is an oblong 
piece which runs backward, beginning just underneath tlx* front end of 
the patagium, and is joined behind to the epimeron, epm 2 . It is united 
below with a double piece, st, which extends downwards and back- 
wards to the coxae, cj 2 . This piece was determined by Dr. Packard, 
in Attacun, as the sternum, and his nomenclature was followed by Bur- 
gess in his article on Danais. From our study of the Cotton Moth, it 
seems doubtful whether this interpretation can be sustained. The piece 
is double on each side, as can be especially well seen in a ventral view, 
Plate IX, Fig. 1. The same aspect also shows that the two pieces do 
not meet in the median line, but are separated by a clear triangular 
space, behind which lies a pair (a, a) of pieces which separate the coxae 
and meet one another in the median ventral line. These are perhaps the 
real sternal pieces. In any case it is evident that further and extended 
study is necessary to elucidate the real morphology of these numerous 
components of the thoracic skeleton. The epimeron, epm 2 (Plate VIII, 
Fig. 1), is quite large and complicated. It consists of a hard V-shaped 
piece, between tlx- two legs of which is a large, triangular membranous 
area. The anterior leg of the V is much the broader, and joins above 
to the episteriium, and in front to the part marked st, which Packard 
has held for the sternum. The membranous portion between the legs 
presents an inconspicuous structure, which is perhaps a spiracle, although 
this could not be certainly established. The coxal joint, cot 2 , tapers 
rapidly ; examined from the outer surface it appears to consist of two 
pieces ; the anterior piece has been called the coxa, the posterior the 
trochantine by some authors. 
The metathorax (III) is particularly puzzling on account of its very 
complex structure, due at least in part to the development of numerous 
63 CONG 4 
