THE DEVELOPMENT OF PERIPATUS CAPENSIS. 463 
5. This projection had already appeared in the spiral stage 
(figs. 28, 29), but it first becomes conspicuous in this stage 
(fig. 30, d.). It is placed at the level of the eighth somite, 
and consists simply of a thickening of the dorsal and lateral 
ectoderm. 
6. This process is shown in its two first stages in figs. 33 and 
34, st. In fig. 33 the posterior margins of the buccal opening 
are beginning to grow in beneath the anterior margins ; the 
same feature being shown more clearly in fig. 34, st. 
7. These pits are caused by an ectodermal invagination 
which will give rise to the slime glands. 
8. These two perforations (fig. 33, o. s.) are actual perfora- 
tions leading through the body wall into the body cavity of the 
third somite (somite of the oral papillae) ; they become the ex- 
ternal openings of the salivary glands. 
Stage F (figs. 35, 36). — The next stage, which is also found 
in October in England, is very close to the previous one, and 
I have only thought it necessary to figure a ventral view of the 
head (figs. 35, 36). Fig. 35 is from a specimen slightly younger 
than fig. 36, in fact from a specimen intermediate between this 
stage and the previous stage. It has already been referred to 
as showing the grooves in the brain ( c . g.), which first appear in 
stage E. The main features of interest in this stage relate 
to the head and anterior somites. 
(1) The lips bave become very conspicuous and folded (fig. 36) ; 
they have extended on to the ventral surface, passing inwards 
between the jaws and oral papillse, behind the openings of the 
salivary glands, which they have completely covered up, and 
finally have united with one another in the median ventral line, 
so as to form the posterior part of the adult lips. 
Fig. 35 is especially interesting as showing an earlier phase 
in this growth. In this figure the folds have not yet reached 
the middle line, and are still very inconspicuous behind the 
salivary openings (o. s.), which are still exposed. 
(2) The cerebral grooves (fig. 36) have become much deeper, 
and their opening reduced to a narrow slit, ending behind in 
the mouth and slightly dilated in front. 
