MILIOLIDAE - Acta Palaeontologica Polonica

30 EWA LUCZKOWSKA
Studying the sections of forms, from the juvenile to the adult or
gerontic one, in different species, or observing the developmental stages
of individual specimens, we can arrive at the following conclusions:
1) The size of test does not depend on the number of chambers but,
above all, on the size of the proloculus. The larger the proloculus, the
fewer are the chambers in specimens of the same size or, in other words,
the juvenile stage of the mega I or mega II generation may be the same
size as the adult stage of the micro ~eneration. This is particularly well
seen in the genera marked by the presence of three generation, Le. in
Quinqueloculina, Triloculina and Pyrgo (e.g. Quinqueloculina anagallis,
Text-figs. 7, 8; Q. buchiana, Text-figs. 12, 13; Q. lentica, Text-fig. 18;
Q. parakneriana, Text-fig. 19; Q. pseudobuchiana, Text-fig. 20; Triloculina
neudorfensis, Text-fig. 46).
2) In the genus Quinqueloculina, producing the massiline adult (or
gerontic?) stage (Part I, p. 346) such forms are met with that their membership
in a given species is determined by the quinqueloculine i.e. juvenile
stage only, since the massiline forms of various species closely
resemble each other in shape. For example, Quinqueloculina buchiana MS,
Q. pseudobuchiana MS and Q. haidingeri MS or Q. akneriana MS, Q. triangularis
MS and Q. parakneriana MS are very much alike. At the same
time the quinqueloculine stage is different in each of these species, in
whose populations it besides prevails most frequently (except for Q. haidingeri,
found mostly as MS), owing to which they can be distinguished
without resorting to sections. This can be interpreted in two ways: either
the genus Massilina actually exists and then the various shapes of the
juvenile stage seen in the sections of similar forms indicate their polyphyletic
origin or Massilina represents only an ontogenetic stage of Quinqueloculina,
isomorphic in different species. The latter view has been
assumed in the present work (see Part I).
3) As can be seen from sections, in a number of genera some species
do not differ in their juvenile stage and their individual characters do not
differentiate before several initial chambers have been developed. For
example, in Cycloforina contorta and C. lachesis tubular chambers occur
in the juvenile stage as in C. gracilis and C. lucida (Text-figs 26, 28) and
only in a later stage angular edges appear in C. contorta and C. lachesis,
but not in the other two species. Tubular chambers of the juvenile stage
are also observed in other species which have edges or ribs in the adult
stage: Lachlanella schroekingeri (Text-fig. 33/3, 4), L. undosa (Text-fig.
33/5, 6), Cycloforina badenensis (Text-fig. 25), Triloculina intermedia
(Text-fig. 46/4), T. neudorfensis (Text-fig. 46/3), etc. In the genera Miliolinella
and Varidentella, which are characterized by a turn of the coiling
axis in the juvenile stage, this stage has a similar form in different
species. It resembles Miliolinella circularis in appearance (e.g. in Varidentella
reussi, Part I, PI. XIII, Fig. 3) and is very often identified as that