of the Lower Malm of Aargau. 59 
generally found with the ammodiscoidal forms, but, unfortu- 
nately, only in fragments not sufficient to determine the species. 
Some shells described as Rotalia and EHndothyra may be 
associated with the polythalamous Trochammine. ‘The tests 
are very variable in general shape, forming more or less 
elevated conical spirals, composed of numerous regularly- 
increasing chambers, finely arenaceous, the small particles of 
quartz or calcareous materials imbedded in a pure white, 
sometimes siliceous and transparent, but generally calcareous 
ochreous cement. These fossils belong probably to some 
already described species (7. inflata, T. squamata, T. coro- 
nata, T. vesiculata, T. Reuss’). From the Bathonian rocks, 
where they appear for the first time in greater number, they 
ee through the Upper Dogger and the Lower and Middle 
alm. 
Figs. 41 and 42 (Pl. III.) represent an interesting variety 
uniting the typical 7. constricta with the regularly convoluted 
conical types and the polythalamous discoidal Trochammine, 
like a form figured by Karrer from the Vienna basin *. 
Comparing the rhizopodal fauna of the Argovian Lower 
Malm with that of other countries, it surprises one to see that 
several of the most common Foraminifera of the Aargau have 
as yet not been discovered anywhere else, while 7. incerta 
seems to be present everywhere. 
The only species with almost equally wide distribution 
is a Textilaria or Plecanium, first described by Giimbel from 
the Streitberg sponge-beds as Textilaria jurassica, varieties of 
which (known as T. franconica, Giim., 7. Triggert, Schw., T. 
flewa, K. & Z., T. helveto-jurassica, K. & Z., T. scyphiphila, 
Uhl., 7. argoviensis, Haeus., &c.) are met with in almost 
every zone of the Malm. ‘The broader varieties unite the 
lanceolate 7. jurassica with some from the Cretaceous for- 
mation. — 
Before concluding, a few remarks on the different families 
of Jurassic Foraminifera may be of interest. 
As stated before, the rhizopodal fauna of the Swiss trans- 
versartus-beds is very rich in species and varieties compared 
with older zones of Liassic or Middle Jurassic age. Many of 
the widely-distributed types of Lagena, Nodosaria, Dentalina, 
and Cristellaria can be traced throughout the whole Jurassic 
series, beginning with the lowest Sinemurian limestones of the 
valley of the Reuss; while the oldest Liassic beds, the cele- 
brated insect-marls of the Hettangian étage, were extremely 
poor, and vielded only a few fragments of Cristellarians and 
spiroloculine Mihola. 
* Loe, ct. pl. i. fig. 8. 
