54 Dr. R. Haeusler on the Trochamminz 
The same regular form is figured in Carpenter’s Introd. 
Foram. (pl. x. fig. 2). Although the Carboniferous specimens 
are generally less regular, Brady * mentions a discoidal 
variety, the test of which, however, is much more sandy and 
calcareous than in those from the Lower Malm. 
- The usual diameter of the Argovian specimens is 0°35 
millim. 
Kiibler and Zwinglif describe a constant elliptical variety 
(Cornuspira elliptica) from the Lower Bathonian, and a similar 
compressed variety {| from the Lower Argovian (C. con- 
cava), and Karrer a corresponding form from the Vienna 
basin §. 
In the beds A of the Frickthal I found several specimens 
with a somewhat similar mode of growth; but the first part 
of the shell is discoidal, as in the normally developed variety ; 
the elliptical arrangement begins only with the third or fourth 
convolution. ‘The microscopical structure is the same as in 
the typical 7. incerta reg., as well as the total length and 
diameter of the tube (Pl. III. figs. 6, 7). In one specimen, 
length =0°42 millim., diameter of tube (last convolution) = 
0:04 millim., number of convolutions 6-7. 
In another specimen the oldest part of the shell is elliptical 
and becomes gradually discoidal. 
These deformed shells pass possibly into TZ. pusilla. 
Often the youngest part of the last convolution becomes em- 
bracing and leaves the plane, as in Pl. III. figs. 4, 5. 
Distribution. In the beds A, B, and C of the Aargau, but 
also of the Cantons Schaffhausen and Solothurn, and the upper 
zones of the Malm (Argovian II. and III., Sequanian L., &c.). 
Not common. 
B. Trochammina incerta wreg. 
Test free, irregularly convoluted, composed of a non-septate 
cylindrical tube of almost invariable diameter. Convolutions 
few, in one plane; aperture small circular, or large crescentic. 
Test finely arenaceous, built up of numerous minute grains 
of quartz-sand, imbedded in a whitish or sometimes ferrugi- 
nous cement. 
This variety comprises a great number of forms, passing 
from J. incerta reg. to T. gordialis and T. filum. From 
the first they differ chiefly in their thick, more arenaceous, 
opaque or but slightly transparent test, and the small number of 
* Brady, Monogr. Carb. & Perm. Foram. p 71, pl. ii. fig. 13. 
+ Kubler & Zwingli, 7. c. p. 17, pl. ii. fig. 3. : 
{ Loe. ett. p. 24, pl. iii. fig. 3. 
§ Karrer, /. c. p. 494, pl. i. fig. 10. 
