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the two terminal pieces. The larger and more rigid of the two, which is 
also the more lateral and the more ventral in the fully flexed position of 
the sympodite, is obviously the exopodite. The more medial and more 
dorsal segment, less well developed and almost hidden by the exopodite 
when the uropod is closed, is the endopodite. 
The gill-directed surface of the uropodal sympodite is covered with soft 
cuticle and is obviously branchial in function, for between the main blood- 
vessels, which run antero-posteriorly at each border, is arranged a great 
number of transversely coursing vessels exactly like those in the exopodites 
Fig. 11. — Ventral aspect of the pleon of Glyptonotus after 
removal of the appendages. Natural size. Somewhat 
schematised in order to bring the uropodal and the pleo- 
podal articular foramina into view at the same time. 
An articular spur is present on the posterior-medial 
border of each pleopodal articular foramen ; a similar spur 
occurs on the anterior border of the two uropodal articular 
foramina. As can also be seen in the previous figure, the 
posterior articular foramina are seen to be increasingly 
twisted forwards. 
and endopodites of the pleopods. On similar grounds one infers that the 
ventral aspect of the telson is a respiratory surface. 
The flexor and extensor muscles which move the uropod are more feeble 
than those which move the anterior three pleopods. They lie in a special 
compartment of the pleon, lateral and slightly posterior to those occupied 
by the muscles of the fourth and fifth pleopod. On the medio- ventral aspect 
these muscles are covered simply by soft cuticle, through which they are 
easily visible ; the medial border of the articular foramen in the sixth 
segment is similarly non-calcified. 
The Cephalosome. 
When the body is transversely divided along the line of the first 
movable thoracic articulation the internal hard structures of the anterior 
