Morphology of the Myriopoda. 343 
of the “ basilar segment” of Newport, but appear to have in 
adult life no tergite of their own *. 
The second pair of malipedes or last pair of mouth-appen- 
dages are the poison-fangs ; they are the “ second auxiliary 
lip” of Savigny, the “ mandibles or foot-jaws” of Newport 
and subsequent authors. The dorsal plate, or what may be 
called the second malipedal teryite, is the “ basilar and sub- 
basilar plate’ of Newport. 
As to the number of segments in the head of Chilognaths, 
both morphology and embryology prove that there are but 
three, in the Chilopoda five. Newport’s observations on the 
young recently-hatched Geophilus (his pl. xxxiii. fig. 3) show 
that the subbasilar plate is the tergum or scute of the fifth 
segment ; and the basilar plate is consequently the tergum of 
the fourth segment or second malipedal segment. The ster- 
nite of the subbasilar plate is usually a very large plate, 
deeply indented in front in the middle, with teeth on each 
side, and forms the “ labium” of Newport. It may, for con- 
venience in descriptive zoology, be termed the ‘ pseudo- 
labium.”’ 
As embryological proofs of our morphological views may 
be taken the admirable researches of Metschnikofft on the 
development of Geophilus. His Taf. xx. fig. 4 shows 
plainly the four pairs of mouth-appendages behind the an- 
tenne, the latter developed, as in Hexapods, from the pro- 
cephalic lobes. His fig. 15 shows that the pleurum and 
tergum of two posterior (or fourth and fifth) cephalic arthro- 
meres, with their appendages, are the primitive scuta of the 
proto- and deutomalar arthromeres, which at this period have 
coalesced and are intimately united with the procephalic lobes. 
His fig. 18 shows that at a later period the primitive scutum of 
the fourth cephalic segment has disappeared, or at least is 
merged into the fifth primitive scutum or subbasilar plate of 
the adult. An examination of Metschnikoft’s paper will prove 
conclusively that Newport’s views as to the subsegments of 
the Chilopods are not well founded in nature, and that they 
are merely for the most part simply adult superficial 
markings. 
The following Table will serve to indicate in a comparative 
* Balfour also states, as we find after writing the above, that the basilar 
plate is really the segment of the poison-claws, and may fuse more or less 
completely with the segments in front of and behind it, and the latter is 
sometimes without a pair of appendages (Lithobius, Scutigera). (Comp. 
Embryology, i. p. 225.) i 
+ “Embryologisches, tiber Geophilus,” yon Elias Metschnikoff, Zeit- 
schrift fiir wissenschaftl. Zoologie, xxv. p. 3513 (1875), 
