of the Lower Malm of Aargau. 357 
Trochammina incerta, var. crassa. (Pl. XV. fig. 2.) 
_ Cornuspira crassa, K. & Z. 1. c. p. 19, pl. ii. fig. 2. 
Test free, discoidal, regularly convoluted in one plane. 
Convolutions few, four or five, of nearly uniform width. 
Aperture large, simple. . 
Test thin; cement calcareous, colourless. Surface smooth. 
Diam. 0°15 millim. 
The same beds C contain the compressed varieties (Cornu- 
spira elliptica, and C. concava, K. & Z.) and a form resem- 
bling C. colithica, Schm., in greatest number. 
APPENDIX. 
There remain two species of arenaceous Foraminifera, which 
belong probably to the genus Trochammina. 
The first (figs. 17 and 18) consists of a simple cylindrical 
tube, which at its commencement forms a completely closed 
ring or a part of a spiral. ‘The test is fine, arenaceous ; 
cement calcareous, colourless. Surface smooth. L. 0:18 
millim. 
This peculiar form resembles 7. (Amm.) jilum, Schm., or 
Uncinulina polymorpha, Terq. 
Another doubtful species (fig. 19) is free, crozier-shaped, 
multilocular, the septa hardly visible externally. 
Test very fine, arenaceous, subtransparent ; cement calca- 
reous. Surface smooth. lL. 0:2 millim. 
The few small imperfect specimens are not sufficient to 
describe these forms exactly ; but as the shell-substance re- 
_ sembles that of 7. (Amm.) incerta of the same beds C, they 
may at present find their place among the polythalamous 
Trochammine nearest to T. lituiformis, Brady, and T. helveto- 
qurassica, Hiusl. 
EXPLANATION OF PLATE XV. 
Fig. 1. T. (Ammeodiscus) incerta, var. granulosa. 
1g. 2, T. incerta, var. crassa. 
Fig. 3. T. incerta, var. gracilis. 
Fig. 4. T. incerta, var. megaspira. 
Figs. 5-7. T. inflata. 
Figs. 8, 9. T. globigerinordes. 
Figs. 10, 11. T. helveto-jurassica. 
Figs. 12,13. T. (Hormosina) chrysalis. 
Fig. 14. T. (Hormosina) transversaru. 
Fig. 15. T. (Webbina) irregularis. 
Fig. 16. T. ( Webbina) planorbiformis. 
re I T. (Ammodiscus) ? 
Fig. 19. T. (Ammodiscus) ?, sp. 
