DEVELOPMENT OF PERIPATUS CAPENSIS. 
773 
or spindle-shaped cells. The lateral projections of the digestive tract adhere to the 
inner layer at the interspaces between the undulations. The wall of the digestive tract 
is covered with a layer of cells continuous with and similar to those of the inner layer 
of the members, and probably a reflection of the same layer. The members as they 
project further and further outwards become hollow loops, which later become solid by 
proliferation of the cells of the inner layer. The large cavity in the cephalic lobes 
corresponds exactly to the cavities formed in the members. The digestive tract is in 
this stage filled with darkly pigmented rounded particles and fine granules. The tract 
assumes gradually a brick-red colour, which increases in intensity, and eventually in 
later stages renders the embryo very conspicuous. 
In the next stage observed (Plate LXXV. fig. 3) the embryos have reached a length of 
from 5 to 5‘5 millims. Since the most fully developed specimen was no longer than this, 
it is probable that this is about the length of the young when born. All the pairs of 
members are formed, but the anterior are more perfectly shaped than the posterior. The 
antennae show a commencement of jointing ; the cephalic lobes show a line of depres- 
sion, indicating more plainly a division into two segments. The second pair of members 
is still the largest, but the first is somewhat smaller than the third. A bifid saddle of 
yelk is seen on the dorsal surface of the embryo opposite the seventh, eighth, and ninth 
pairs of members. More investigation is required about this yelk-mass ; it was not 
observed in the early stage (fig. 1) at all. It was observed in one specimen of the very 
late stage (fig. 10), but often not in intermediate stages. It may have been overlooked, 
but possibly is not constant. The embryo in the stage shown in fig. 3 is coiled up 
within its envelope in the manner shown in fig. 4, and retains this posture till the 
latest stage observed. The body is bent round in an oval form, and the posterior ex- 
tremity bent up and applied against the front of the cephalic lobes between the pair of 
tentacles. The full number of body-members having been attained at this early age, 
the further advance of the front segments only will be followed, viz. those which form 
the parts about the mouth. Buds (fig. 5, m ) grow out backwards from the hinder part 
of the cephalic lobes. In one case, shown in fig. 5, the buds appeared double ; at all 
events, only the larger one develops. The first pair of limbs have shrunk a little in 
proportion to the rest, though the second still remains very large, as is seen in fig 6, 
which represents a lateral view of nearly the same stage as fig. 5. When the members 
are said to shrink, it is intended of course that the other members outgrow them. The 
first pair of members gradually turn inwards (fig. 7, i), and are overlapped by the elonga- 
tions of the processes of the cephalic lobes (m). A rounded process grows downwards 
over the mouth from the front wall of the head in the median line; a transverse 
elevation arises beneath the mouth opposite to this and between the upper edges of the 
second pair of members. The eyes appear (e) at this stage as oval aggregations of cells 
derived from the internal masses of cells of the head, and covered externally by trans- 
parent rounded elevations of the epidermic layer, the future corneee. 
The first pair of members pass further inwards (fig. 8), and their claws appear. The 
