lye Macieay MemorraL Vouvume. 
the form of a conical muscle arising from the carapace behind and below the origin 
of the long adductor of the mandible, and inserted by a long slender tendon into the 
external aspect of the basal region of the appendage. 
6. Latrinsic muscles of the mandible (figs. 8 and 10). 
The doxg adductor is a large conical muscle arising from the dorso-lateral region 
of the carapace a short distance cephalad of the cervical groove ; it is inserted by a 
long calcified tendon into the postero-internal angle of the mandible. 
The short adductor is a small fan-shaped muscle arising from the cephalic 
apodeme and radiating outwards from its origin to a wide fleshy insertion on the 
inner or concave side of the mandible. 
The external adductor has an extensive origin from the inner surface of the 
carapace anterior to the cervical groove ; its short fibres pass directly mesiad to their 
broad fleshy insertion on the outer edge and adjacent part of the ventral or convex 
surface of the mandible. 
The Zong abductor is a band-like muscle arising from the cephalic apodeme and 
g } 
passing outwards and forwards to its insertion in the antero-external angle of the 
mandible. 
The short abductor arises from the lateral surface of the cephalic apodeme, its 
fibres diverging to their insertion in the posterior edge of the mandible. 
7. ALuscles of the antenna (figs. 8, 10, 24, and 25). 
The antenne of Palinurus are remarkable for their great size and for the fact 
that their proximal podomeres (coxopodites) have concresced with one another and 
with the carapace to form a flat horizontal plate, the pseudepistoma, on which the 
renal apertures are situated. It has been pointed out by one of us* that the adjacent 
or mesial walls of the coxopodites are represented by the vertical, two-layered zxternal 
coxal plate which projects inwards (dorsad), in the middle line, from the pseudepis- 
toma, while their lateral walls are represented by the oblique external coxal plates 
which project wards, in like manner, at the junction of the pseudepistoma with the 
carapace.t 
Connected with the pseudepistoma and the coxal plates are certain ligaments 
and functionless muscles which we consider to be the degraded representatives of the 
muscles by which the coxopodites were moved in the ancestors of the genus. 
* Parker, ‘‘On the Structure of the Head in Palinurus.” Trans. N.Z. Inst. Vol. XVI. 1883, p. 297. 
+ It is quite possible that the coxal plates represent, not portions of the coxopodite itself, but the insertions of 
calcified tendons which have become hypertrophied in order to serve as points of origin for the great antennary muscles. 
