30 
PA UROPODA. 
presented by the antennae of Diplopoda. Even Polyxenus has typi- 
cal diplopod antennae, and those of the related genera Eophoproctus 
and Saroxenus* are still more closely similar to the normal type. 
As a class the Pauropoda are one of three coordinates under the 
branch or subphylum Progoneata, the others being the Diplopoda and 
Symphyla, perhaps more nearly related to each other than either is to 
the Pauropoda. It seems strange that the evident and striking diplo- 
pod homologies of the Symphyla have been so long ignored. The 
sclerites of the head, for instance, are exactly those indicated by a 
comparative study of the sutures which appear in the various diplo- 
pod orders, while the anal stylets which have seemed so remarkably 
thysanuran, may easily be the homologues of those of the diplopod 
orders Monocheta and Coelocheta, which are again homologous to the 
anal bristles of the Merocheta. 
The coordinates of the Progoneata are the Opisthcgoneata, contain- 
ing the Hexapoda and Chilopcda. The contradictory opinions drawn 
from the morphologic researches of recent years give increasing 
strength to the suspicion that homologies outside of these lines can- 
not be safely maintained, and that a common origin of the Opisthog- 
oneata and Progoneata with the Arachnida, Crustacea and Malacopo- 
da is as remote as the annelid series, so that arthropodous connecting 
links may never have existed. It will accordingly be necessary to 
subdivide the group Arthropoda, with the result that if a relation- 
ship of the Progoneata with the Opisthcgoneata be allowed, there 
will be at least three phyla or subkingdoms. The first and perhaps 
the most primitive is the Malacopoda, to contain the Peripatidae. The 
second consists of the Progoneata and Opisthcgoneata, for which 
complex the name Eabrata is proposed. The third phylum Branchiata 
will probably not long suffice for the diverse forms which it is as yet 
supposed to contain, though the adoption of varied and parasitic 
habits in the Crustacea and Arachnida weakens the force of analogy 
in estimating the value of structural and developmental differences. 
THE SPECIES OF PAUROPODA. 
1. Pauropus huxleyi Lubbock. Reported from various parts of Europe, 
England, Austria, Russia and Italy ; also from Massachusetts (Kenyon), 
and Pennsylvania (Ryder). 
2. Pauropus lubbockii Packard. This is thought by Kenyon to be the same 
as the preceding ; but no adequate description has been published. 
3 . Pauropus impar, sp. n. Distinct in that the external flagellum of the 
stout branch of the antenna is not half as long as the other ; the glob- 
ulus is entirely sessile ; the last pair of tactile hairs are not as strongly 
* A new genus soon to be published in the American Naturalist. It is 
based on 5. scandens, a large Liberian species with long antennse and four 
large tufts of bristles to each segment. 
