178 KEPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
From each of the two very large prothoracic spiracles, besides two 
small tracheae, a very large barrel-shaped dilated trachea is directed 
downwards to the sternum. It communicates directly with the large 
spiracle as the point of a needle or knife when passed through the 
spiracle entered directly into this trachea. 
CHAPTER IX. 
THE AIR-SACS OF LOCUSTS WITH REFERENCE TO THEIR 
POWERS OF FLIGHT. (Plate I.) 
In the ninth chapter of our First Report we briefly described the dis- 
tribution of the air sacs in the locust, and indicated that its great powers 
of tli.niit were largely due to the fact that this insect is an aeronaut. 
For want of space we did not discuss what had been done by others in 
this direction, nor did we describe the mode of distribution of these air- 
sacs in other insects. 
These air-sacs were first noticed by Swammerdam, and afterward by 
Sir John Hunter. Swammerdam, a Dutch naturalist, whose famous 
work entitled The Book of Nature, appeared at Leydeu in 1737, first 
described and figured them in a lamellicorn beetle (Geoirupes nasieornis). 
Afterward they were discovered by Sir John Hunter in the bee, and sub- 
sequently Prof. K. Sprengel 2 " discovered them in other insects. They 
were in 1828 described and illustrated in a very elaborate and detailed 
way by Straus Durckheim in his grot work on the anatomy of the 
cockchafer. 218 Afterward special attention was paid to them by .Marcel 
de Serres, who published a detailed account and figures of the air-tubes 
and sacs or vesicles of a grasshopper (Truxalis nasutus). Marcel de 
Serres's figure is truer to nature than that of L. Dufour, published in his 
work on the anatomy of the Orthoptera, 219 &c, and show well the great 
number of these air-sacs as seen in a dorsal view of the insect. The 
English anatomist, G-. Newport, has also described and figured the air- 
sacs in the abdomen of the male bumble-bee in the Philosophical Trans- 
actions of the Royal Society of London, 183G. 
From Newport's article " Insecta," in Todd's Cyclopaedia of Anatomy 
and Physiology, we take the following statements regarding the distri- 
bution of these sacs in different insects. 
These air-sacs are found most developed in bees, wasps, &c. {Hymen- 
optera), moths and butterflies, flies (Diptera), and some beetles and some 
bugs (Hemiptera), though in the immature or larval state of all these 
insects there is not the slightest trace of them. They thus do not occur 
217 Commentarius de partibus quibus insecta spiritus ducunt. Lipsiaj, 1815. 
sl8 Consid6rations gen6rales sur l'Anatomie comparee des Animaus articules. Par Hercule Straus- 
Diirclrheim. Paris, 1828. 
J19 Eecherches anatomiques et physiologiques surles Orthopteres, les Hymenopteres et les ifevrop- 
t&res ; par M. Leon Dufour, Memoires Mathematiques des Savants etrangers, Paris, 1841. 
