348 Dr. A. S. Packard, Jun., on the 
of the Pauropoda assigned them by Sir John Lubbock, in 
regarding them as Chilognaths, with aberrant features which 
would throw them into a suborder of the latter group. 
The Systematic Position of Scolopendrella.—This singular 
form is usually regarded as a Myriopod, while Mr. Ryder re- 
fers it to a distinct order, Symphyla. We have already* 
given our reasons for the view that it is a ThysanuranT, with 
only superficial resemblances to the Chilopod Myriopods. 
Our fresh studies on the latter confirm our opinion that 
Scolopendrella is a Hexapod. ‘The mandibles and maxille, 
the former especially, are like those of the Thysanura rather 
than the Myriopods, not being divided into two parts (stipes 
and cardo). Itseemsto us that Scolopendrella with its nume- 
rous postcephalic legs may fulfil the phylogenic requirements 
of the early embryo of Hexapoda and Arachnida in which 
there are a number of embryonic primitive abdominal appen- 
dages. Thus it preceded Campodea as a stem-form. 
Genealogy of the Myriopoda. — The pseudo-hexapodous 
larval forms of Chilognatha, including the Pauropoda and the 
early germ of the Chilopoda (Geophilus), indicate that the 
many-legged adults were derived from what we have called a 
Leptus-torm ancestor. Our present knowledge of the embry- 
ology of the Myriopoda shows that, unlike the Arachnida and 
Hexapoda, the embryo is not provided with primitive transi- 
tory legs. There seems then no direct proof that the Myrio- 
poda had an origin common with that of Insects and Arachnida, 
from a Scolopendrella-like, and perhaps still earlier Pertpatus- 
like ancestor ; but from a six-legged form, which, however, 
may have been derived from some worm-like ancestor. The 
Leptus-torm larve of Myriopoda, with their three pairs of 
cephalic appendages and six legs, may then be the genealo- 
gical equivalent of the six-legged Nauplius of Crustacea ; 
which type is generally believed to have originated from the 
worms. 
A genealogical tree of the Myriopods would then be simply 
two branches, one representing the Diplopod and the other the 
single-paired type (Chilopoda), both originating from a 
Leptus-like six-footed ancestor (¢. e. with three pairs of 
cephalic and three pairs of postcephalic appendages). 
Dr. Erich Haase, in his “ Beitrag zur Phylogenie und 
Ontogenie der Chilopoden,” publishes a “ Stammbaum der 
* ¢ American Naturalist, xv. p. 698 (Sept, 1881). 
+ Compare the excellent figures of the mouth-parts of Scolopendrella 
in Dr. I. Muhr, ‘ Die Mundtheilein Scolopendreila und Polyzonium,” 10er 
Jahresbericht tiber das deutsche Staats-Gymnasium in Prag-Altstadt, 
1881-82. Prag, 1882. 
ils 
