127 
an obtuse apex, segments eighteen to twenty, the apical segments slightly 
emarginate backwards in the middle line ; pleurm fourteen to sixteen, the 
facets of the anterior segment large, and rather triangular; limb narrow, 
striate. Test and its sculpture unknown. 
Obs . — This species was originally described by Mr. R. Etheridge from 
a very small and therefore probably young specimen. Such a one I have 
now before me from the Star Carboniferous Basin, Queensland, collected by Mr. 
R. L. Jack, corresponding in every particular, but one, with the larger New 
South Wales examples. The difference lies simply in the number of somites 
in the pygidium, the Queensland example possessing but eight to ten in the 
axis, our specimens, on the contrary, being constantly eighteen to twenty. 
Eurthermore, those of the northern form are all emarginate Imckwards in the 
middle line, except the two anterior segments. In the southern variety it is 
the apical six or eight which are so emarginate. The probable explanation of 
this is that of age. There are also indications of indistinct tubercles along the 
sides of the axis at the distal or apical end, but so indefinite that too much 
stress need not be laid on them. 
Erom the British species of JPhiUipsia the present Trilobite is distin- 
guished by the much more oval and longer body, generally larger number of 
segments, especially in the pygidium, and particularly in the form of the 
glabella. It approaches nearest to P. Eich waldi, but the glabella of P. diihia 
is again longer and narrower, and our form does not jiossess genal spines, nor, 
so far as known, a granular ornament to the test. The resemblance chielly 
lies in the somewhat triangular pygidium, although I have never seen a 
mucronate variety from Australian rocks. In similar terms P. duhia differs 
from the Russian species described by Valerian von Moller,^ from the Car- 
boniferous Limestone of that country. 
The descriptions of the American species I have not full access to, but 
in its proportions P. duhia resembles P. sangamonensis, M. and W.," but the 
glabellas of the two species are wholly unlike. The great increase in the 
number of coalesced axial segments in the pygidium is similar in P. major, 
Shumard, but the very deep and pointed limb at the axial apex is not j^resent 
in our species. 
‘ Uber die Trilobiten der Steinkohlenformatioii des Ural, &c. Bull. Soc. Imp. Nat. Moscou, 1867, No. 1. 
^ Vogdes, The Genera and Species of North American Carboniferous Trilobites. Ann. N. York Acad. 
Sci., IV, t. 3, f. 8. 
• Meek in Hayden, Final Report U.S. Geol. Survey Nebraska, 1872, Ft. 2, t. 3, f. 2, 
11a 64—92 K 
