1881 .] 
155 
[Burgess. 
differs from that of Danais in being much longer, and it turns at 
a sharp angle into the anterior branch, instead of gradually. 
Fig. 3. Aorta of Chaerocampa sp. x. 4K 
In a Hawk Moth (Chaerocampa), fig. 3, the aorta ascends, at a 
small angle from the perpendicular, to a point just behind the 
meso-scutellar suture, then turns back on itself for about a third of 
the distance, where it turns abruptly forward, then more gradually 
downward, again abruptly backward nearly to the posterior 
branch, and with a wide curve, jiasses forward a second time, 
finally bending downward toward the oesophagus. The anterior 
branch thus forms a broad and angular S, and is certainly a most 
astonishing feature. The point of union between the two branches 
forms a vertical aortal chamber, but I have not made out whether 
it is open from top to bottom, or if the two branches are really 
distinct, their adjacent walls being simply soldered together. 
Fig. 4. Aorta of Agrotis jaculifera, x 10, 
showing also outline of thorax. 
Fig. 5. Aorta of Retinia frustrana, 
with outline of thorax, x 25. 
In Agrotis jaculifera, fig. 4, the posterior branch ascends in an 
open S-curve, then turns back on itself as in the Hawk-moth, but 
