16 GENEEAL DEVELOPMENT OF THE EMBRYO. 



become much reduced by the approximation of the ventral 

 swellings at the base of the jaws (cf. figs. 35 and 36,^. s.). 



(4) The prseoral 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 December 

 (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 («?), 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 (5/. g.) which, however, are directed more 

 dorsally. The salivary glands are, as I have said in my pre- 

 liminary paper, the nephridia of the third somite, i, e. the somite 

 of the oral papillae. 



