1205 
Similar relations as exist between amphibole and augite, which 
are found with the minerals bronzite and anthophyllite, we hope in 
future to discuss in detail. 
In addition we wish to make a remark on some R6xtarNogrammes 
published here, where a bright ring is visible round the black 
central spot. This occurs in those cases, where by the erystal or by 
the glass, upon which in some cases the crystal-plates were fixed, 
secondary RÖNTGEN-rays are emitted, giving a veil of the photographic 
image; this veil will be intensified of course by the action of the 
intensifying screen. Now this screen is perforated in its central part, 
for reasons formerly explained; thus in this part of the photo the 
said veil will wot be intensified by the action of the sereen, and a 
brigbt ring will appear round the black central spot. From this 
it follows, that if the crystals must be fixed upon a glass-layer, it 
will be of advantage to keep this glass-layer as thin as possible, 
because the secondary radiation of a thinner layer will be less 
intensive than that of a thicker one. 
Laboratories of Physics and of General and 
Physical Chemistry of the University. 
Groningen, January 1916. 
Palaeontology. — “Some young-pliocene Ostracods of Timor”. By 
Miss E. C. Fran. (Communicated by Prof. J. W. Morr). 
(Communicated in the meeting of Jan. 29, 1916). 
The Ostracods, which will be discussed in this essay, have been 
obtained from washings of tertiary clay of the left bank of the 
Mota Talau near Atamboea in Timor. This clay, which according 
to the label which went with it, was formed in the latest part of 
the Pliocene, was collected by Prof. Dr. G. A. F. Mortereraarr and 
Mr. F. A. H. WEeECKHERLIN DE Marez Ovyers m.e. on the expedition 
which took place during 1910—1912 to the isle of Timor under 
the auspices of the former. The leader kindly allowed me the use 
of the material, for which kindness I express my thanks to him here. 
The rests of the different Ostracods have been preserved excel- 
lently. Very often they are quite transparent, often white, sometimes 
black and occasionally blue. This last colour is very likely caused 
by vivianite. By a treatment with hydrochloric acid appeared, that 
the transparent ones consist also almost quite of carbonate of lime. 
This last kind of valves are particularly fit to mark the “Innen- 
rand”, the “Verwachsungslinie’ and the “randständige Porenkanäle” 
AOR ps 1025 14 ps. 2): 
