464 ADAM SEDGWICK. 
(3) The ingrowth of ectoderm into the mouth-opening is 
completed in fig. 35. In fig. 36 the mouth-opening has become 
reduced to a narrow slit by the approximation of the ventral 
swellings at the base of the jaws (cf. figs. 35 and 36,.;. s.). 
(4) The praeoral or cerebral lobes, which were distinctly 
bilobed and separate in the previous stage (fig. 33) , have now 
again become quite continuous across the middle line (cf. figs. 
33, 35, 36), a shallow groove only marking the original line of 
separation. 
Stage G (figs. 37, 38). — The last stage which I have thought it 
necessary to figure and describe is found in England in De- 
cember (figs. 37, 38). The differences between this and the 
previous stage consist mainly in the growth of parts already 
present. 
The embryo is characterised by its great transparency. The 
full number of appendages is present, and the appendages have 
acquired more nearly their adult form. They are all ringed, 
and the rudiments of claws have appeared on the legs. The 
appendages (fig. 37) are antennae, jaws (now completely hidden 
by the lips) oral papillae, seventeen pairs of legs, and the small 
anal papillae {an. p.). 
The skin presents slight projections, shown as white opaque 
marks in the figure ; these are the commencement of the 
papillae, which cover the skin of the adult. The dorsal pro- 
jection is still a conspicuous object {d), though not so con- 
spicuous as in the earlier stages. 
The integument presents a ringed appearance (fig. 38); the 
rings, however, have nothing to do with the segmentation of 
the body, being far more numerous than the segments. 
The mesenteron is distinctly visible as a wide tube which 
behind passes into the narrow rectum ( R ). The rectum is pro- 
bably lined by an ingrowth of ectoderm through the anus and 
may be looked upon as a proctodaeum. 
The salivary glands (s. g .) can be seen through the skin, and 
have grown some distance backwards. The same is to be said 
of the slime glands {si. g.) which, however, are directed more 
