Mr. J. Wood-Mason on Scolopendrella. 53 
coidal and spherical), and Podocyrt’s. A few specimens of 
well-marked fossilized Dictyochide also occur. Both the 
Polycystina and the Dictyochide, as well as the mass of the 
loose granular material associated with them in the same flint- 
cavities, are more or less metamorphosed by a slight admixture 
of peroxide of iron and calcite, the former substance having 
imparted to the entire structures a bright reddish hue. 
Through the courtesy of Prof. T. G. Bonney, F.R.S., I 
have been enabled to examine a slide of ‘ diaspro ” contain- 
ing Polycystina. These, however, exhibit somewhat less of 
the characteristic structure of the organisms, owing, no 
doubt, to their having become fossilized under less favourable 
conditions than those which existed in the hermetically closed 
flint-cavities. In both cases the polariscope shows the silica 
to have been partially replaced by calcite. 
I have likewise found in material obtained from hermetically 
closed flint-cavities, by far the most perfectly preserved Fora- 
minifera I have ever seen, the shell-structure and chambers, 
with every minutest detail of tubular structure, having been 
converted into chaleedony—the whole mass by reflected light 
presenting a beautifully whitish-blue opalescent appearance, 
whilst by transmitted light it exhibits a rich transparent burnt- 
sienna colour and the well-known fibrous character of chalce- 
dony wherever that substance is most massive, as, for instance, 
within the chambers. The Foraminifera represented belong 
chiefly to the genera Rotalia, Globigerina,and Textularia. I 
may add that, as regards perfection in every minutest detail of 
shell-structure, these specimens greatly surpass in beauty those 
metamorphosed into glauconite, beautiful as they also un- 
doubtedly are. 
1X.—Notes on the Structure, Postembryonic Development, and 
Systematic Position of Scolopendrella. By J. Woop- 
Mason, Deputy Superintendent, Indian Museum, Calcutta. 
THIS interesting and remarkable type of Tracheate Arthro- 
poda was first made known to science in 1839 *, in which 
year the distinguished zoologist Prof. P. Gervais brought to 
the notice of the Academy of Sciences at Paris some speci- 
mens of a small and fragile Myriopod which had been disco- 
vered in the vicinity of the French capital; and founded 
* ¢ Comptes Rendus,’ tome ix, p. 582 (1839). 
