DEVELOPMENT OF PERIPATUS CAPENSIS. 
775 
Newport came to the conclusion that the head in Scolopendra was built up of eight 
segments, with appendages and outgrowths as follows : — 
First segment. Antennae. 
Second „ Eyes and labrum. 
Third „ Dental plates =“ mandibles” of modern writers. 
Fourth ,, First pair of maxillae. 
Fifth „ Second pair of maxillae. 
Sixth „ Mandibles =“ foot-jaws ” of modern writers. 
Seventh „ 0 
Eighth „ 0 
The actual mode of development of the parts is not described. The eye-segment 
may be disregarded, the eyes of Arthropods being now for so many reasons not regarded 
as homologous with appendages. The cephalic lobes, as already described, show early 
traces of a division into two segments, anterior and posterior. The downward growths 
of the hinder parts of the head would appear, then, to be homologous with the man- 
dibles of Scolopendra, and the process between them with the labrum. The oral 
papillse or shrunken second pair of members must most probably represent the foot- 
jaws of Scolopendra, their glands representing their poison-glands, and probably also the 
silk-glands of caterpillars. If this be the case, then the jaws developed from the first 
pair of members must be maxillae; but we have two pairs of jaws developed from one 
pair of appendages, the jaws being evidently merely the modified claws of the ambu- 
lacral members. In Scolopendra , according to Newport, the biting-parts of the maxillae 
are sternal and episternal in origin, the claws terminating the palpi. Are these two 
pairs of jaws homologous with the two pairs of maxillae of Scolopendra , or do they only 
represent one pair 1 If only one pair, then do the oral papillae represent the second 1 
On these questions appears to depend the homology of the mesially indented line 
showing a ridge stretching between the bases of the oral papillae. This, if the oral 
papillae are homologous with the foot-jaws of Scolopendra , represents the second under 
lip of that animal, which is formed of the fused sternal and episternal plates of the 
segment to which the foot-jaws belong, and is slightly notched anteriorly as here. 
Conclusion. 
In the present state of our knowledge concerning the structure of Peripatus , the 
most remarkable fact is the wide divarication of the ventral nerve-cords. The fact was 
considered remarkable and dwelt upon in all mention of Peripatus before the exist- 
ence of tracheae in the animal was known, and when it was thought to be herma- 
phrodite, but it is doubly remarkable now. The fact shuts off at once all idea of 
Peripatus being a degenerate Myriopod, the evidence against which possibility is over- 
whelming. The bilateral symmetry and duplicity of the organs of the body, the 
absence of striation in the muscles, the absence of periodical moults of the larval skin 
MDCCCLXXIV. 5 M 
