392 EXTERNAL ANATOMY OF INSEc?rS. 
11. Fusi (the Spinners). Organs, consisting of two re- 
tractile pieces, issuing from the Mammule, and ren- 
dering the threads *. 
12. SrpHonvti (the Szphonets). Truncated, fistular, se- 
| tiform anal organs, emitting,a saccharine fluid®.— 
Ex. Aphis. 
You. will observe, that when the whole upper-side of 
the Truncus is spoken of, it is called the Thorax ; and as 
in Coleoptera, and some other Orders, the whole of the 
Mesothorax except the Scutellum is covered by the Tho- 
raz, and the whole of the Metathorax by the Mesothorax 
and Elytra—the Thoracic shield may without danger of 
mistake be denominated the Thorax, as it has always 
been. When the whole under-side of the Trunk is spoken 
of, it is called the Pectus. When the three Sternums 
are spoken of together, they may be called the Sternum ; 
and the whole interior elevation of the Pectus may be 
called the Endosternum. 
I am, &Xc. 
* Prare XXIII. Fie. 12. Bl. 15. 
® De Geer ubi supr. t. iii. f. 5, 20, 21. ¢. 
a id 
