MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND 9
down, and melting the surrounding balsam slightly. Then the balsam
enters the chambers, but the specimen needs resetting in the upright
position. The method of filling specimens with balsam by boiling them in
it after their being dipped in xylol, recommended by Pokorny (1958), was
not effective, for balsam in the chambers was softer than that surrounding
the specimen. The method described here is superior to the method
of grinding specimens embedded entirely e.g. in polymers and to that of
cutting them with a razor, as proposed by some investigators (Haake 1964),
in that it enables the worker to check his work constantly, to stop grinding
at suitable moments, and to handle the specimen and correct its
position by melting the balsam in the course of operation. This method
also allows the filling of the chambers with balsam when they are all
open after initial grinding. In whole, unground, fossil foraminifera the
filling of the interior with balsam or any other hardening compound is
rarely effective, since it is enough that a grain of sand sticks in the last
chamber for the inflow of liquid to be stopped. The preparation of sections
by the present method is successful in at least 90 per cent of specimens.
The electrically heated needle used for handling specimens in balsam
was manufactured according to the description given by Triebel (1958,
p. 115, Text-fig. 16). All manipulations were performed with the switch
in the hand so that the current could be switched on or off at any moment
without interrupting observation through the microscope and without putting
the needle aside.
Diagrammatic drawings of whole specimens were made before and
those of their sections after the specimens were ground down. The photographs
of sections taken by means of available equipment were not
accurate enough because of big differences in size between the proloculus
(values of the order of a few microns) and the whole specimen (values
of the order of several millimetres). A total of 437 sections and as many
drawings were made.
All the drawings in text and in plates have been made by the author.
HISTORY OF STUDIES ON THE MILIOLIDAE
The classification of the Miliolidae has been giving trouble to micropalaeontologists
for more than 150 years, Le. since the first attempts were
made to include the foraminifera in Linnaeus's system. At first they
were numbered in various genera containing also other foraminiferal
groups, like Serpula and Vermiculum. It was only in 1826 that d'Orbigny
grouped the miliolid species known at that time into six new genera:
Biloculina, Spiroloculina, Triloculina, Articulina, Quinqueloculina and
Adelosina. Later, in 1839, he separated another new genus, Hauerina. The
definitions of these genera were based on the number and shape of the
chambers visible from the outside and we cannot refrain from admiring