In most insects the leg is built up of nine segments: (1) a broad triangular, sub-globular, conical or cylindrical haunch (coxa); (2) a small trochanter; (3) an elongate stout thigh (femur); (4) a more slender shin (tibia); and (5-9) a foot consisting of five tarsal segments.
P, Coxa of hind leg.
Cox, Coxa or basal segment of the ex', The exopodite of the sixth leg.
The y are really excretory glands, and communicate with the exterior by a very minute aperture on the posterior face of the coxa of the fifth limb on each side.
In 1900 it was shown that the coxal gland of Limulus is provided with a very delicate thin-walled coiled duct which opens, even in the adult condition, by a minute pore on the coxa of the fifth leg (Patten and Hazen, 13A).
In all the embryonic or permanent opening is on the coxa of the fifth pair of prosomatic limbs.
In the same and other leading forms a pair of much-coiled glandular tubes, the coxal glands (coelomocoels in origin), is found with a duct opening on the coxa of the fifth pair of appendages of the prosoma.
- Orifice of foetid glands opening above the coxa of the 4th appendage, not raised upon a tubercle.
- Orifice of foetid glands opening above the coxa of the 3rd appendage, not raised upon a tubercle.
Orifice of coxal gland probably situated at base of coxa of 5th appendage; sternal plate of prosoma minute or absent; no prosternal element underlying the mouth.
These two branches arose from a common basal segment or coxa, the inner surface of which was produced into a strong process underlying the external area.
C, Coxa of fore-leg.
1, Coxa of middle leg.