Parker and Rice—On the Myology of Palinurus Edwardstt, Hutton. 169 
The muscles of the coxopodite arise entirely and those of the basipodite in part 
from the corresponding compartment of the endophragmal system. The compartment 
is bounded in front by what may be called its anterior endosternite, endopleurite, and 
arthrophragm, 7.¢., the plates so called* separating the segment in question from its 
immediate predecessor ; and behind by the posterior endosternite, endopleurite, and 
arthrophragm, which similarly separate it from the next following compartment. 
An oblique plate passes from the anterior endopleurite to the posterior endosternite 
and partly divides the compartment into two chambers—one antero-mesial, the other 
pe ystero-lateral. 
The adductor of the leg is a two-headed muscle: the outer head arises partly 
from the epimeron, partly from the anterior endopleurite ; the inner head arises from 
the posterior endosternite. The fibres of the two heads pass to opposite sides of the 
tendon which is inserted into the proximal edge of the coxopodite on its posterior 
aspect, just behind the place of origin of the podobranchia. 
The adductor of the leg is also two-headed. Both heads arise from the anterior 
endosternite, and the single short tendon into the anterior side of the proximal edge 
of the coxopodite. 
The devator of the leg has a long and a short head. The long head arises from 
the posterior endosternite, the short head from the dorsal region of the coxopodite. 
The tendon is inserted into the dorsal side of the proximal edge of the basipodite. 
The depressor of the leg also has a long and a short head. The long head arises 
from the posterior endosternite, the short head from the postero-ventral region of the 
coxopodite. The strong forked tendon is inserted into the ventral region of the 
proximal edge of the basipodite. 
The muscles of the maxillipedes resemble those of the legs except in detail. The 
abductor and adductor of the exopodite are lodged in the basipodite. 
2. Extrinsic muscles of the swimmerets (fiz. 18). 
oO 
The forward movement of the swimmeret is performed by a double-headed 
extensor which arises from the pleuron and is inserted into the basipodite. The 
backward movement is done by a single large fan-shaped flexor which arises from 
the pleuron just above the extensor and is inserted into the basipodite. The absence 
of articulations to the swimmerets probably allows of a feathering movement during 
the forward stroke. 
* See Huxley, ‘‘ The Crayfish,” p. 158. 
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