MOUTH-PARTS OF THE SHORE CRAB. 123 
with which its sclerite makes a narrow articulation. The second segment of 
the limb, the true coxa, is represented by the region which connects the two 
laciniffi. For the most part it is covered with soft cuticle, but its outer side 
is strengthened by a stout bar, the articular sclerite just alluded to. This runs 
along the outer side of the basal portion of the limb. Proximally it articu- 
lates with a hard piece upon the epimeral region ; near this it is joined by 
the sclerite of the precoxal ridge; distally it has a swelling with which the 
sclerite of the basipoditic (outer lacinial) ridge articulates. On this swel- 
ling stands a tuft of very long setse, which may be called the " coxopoditic 
setffi." The outer lacinia is much large-i- than the inner, and its end is 
expanded and has roughly the same shape ns the large distal endite of the 
first maxilliped. Like the inner lacinia it is prolonged as a ridge across the 
face of the limb, but the ridge has no projection of its anterior edge and its 
sclerite makes a better articulation with the articular sclerite. It represents 
the basipodite. The endopodite has a wide base and a narrow, strap-like, 
blunt-ended continuation, separated by a suture. When the limb is in situ, 
this strap passes in a remarkable way over the shoulder of the mandible, 
lying in a notch, much as the endopodite of the maxillule of the Prawn is 
carried in a notch on the edge of the metastoma. 
The maxillule is attached in a little depression of the body-widl imme- 
diately behind the mandible. Like the maxilla it does not abut upon the 
sternum. It has an external but not a median articulation. 
Besides the coxopoditic setse, which are very long, strong, and thread-like, 
the limb bears on the outside of the endopodite a small patch of feathered 
hairs, at the end of the endopodite another such patch, and on the inner edge 
of the endopodite a fringe of long silky hairs. The lacinise bear on their 
free ends a mass of very strong spines, which on the tip of the inner lacinia 
are curved in the same direction as the lacinia itself. The cuticle of the 
endopodite and basal region is thin, but on the lacinise and their ridges and 
the articular sclerite it is of considerable strength. 
Pearson (13) describes in the maxillule of Cancer four muscles — two outer 
and two inner, a " flexor " and an " extensor " in each pair, the flexors 
arising from the protogastric region of the carapace and the extensors from 
the endopleurites of the endophragmal skeleton.- In Careinus six strands 
of muscle enter the maxillule. Of these, two are inserted on the articular 
sclerite, one at each end of the sclerite of the outer lacinia, and two on the 
sclerite of the inner lacinia, at the base and near the middle. This set of 
muscles appears to be adapted to move the whole appendage inward and 
outward, and to rock each lacinia to and fro in an antero-posterior direction. 
There is also a band of muscle running from the sclerite of' the outer lacinia 
to the middle of the broad part of the endopodite. I believe that this when 
it contracts pulls the lacinia forwards towards the endopodite, which is firmly 
strapped to the mandible by its narrow end. 
