of the Lower Malm of Aargau. 300 
In one of the specimens a broad ring was observed at the 
base of the last chamber. Not common. 
2. Trochammina (Hormosina) transversart’, Hiusl.* 
Test straight, elongated, slender, composed of five seg- 
ments, regularly increasing in length. First segment often 
globular ; younger chambers long, subrectangular, last pyri- 
form. 
Test thin, finely arenaceous, fragile, subtransparent ; cement 
calcareous, colourless; surface smooth. LL. 0°3 millim. 
H. transversarw is found together with the former species, 
but very rare. It is variable, but easily recognizable by 
the thin, finely sandy, smooth test. Both H. chrysalis and 
HI, transversartt occur also in the Upper Argovian and 
Lower Sequanian stages of the canton Aargau. 
If we examine the long list of Upper Jurassic arenaceous 
Foraminifera, the large number of Trochammine is surprising ; 
and it is doubtful if in any other period this genus reached 
such an extraordinary development. 
Fully illustrated notes on the mutual relationship of the 
Jurassic Trochammine, with special regard to the numerous 
intermediate forms and monstrosities, will appear in a future 
paper during the coming winter. 
List of Trochammine from the Argovian zone of 
Ammonites transversarius. 
T. (Ammodiscus) incerta, Orb. T. (prop.) inflata, Mont. 
T. (——) gordialis, J. & P. Lie ) globigerinoides, sp. nov. 
IMME ) charoides, J. & P. T. (——) helveto-jurassica, Héausl. 
( ) vesiculata, Uhlig. 
) Reussi, Uhiag. 
(Webbina) irregularis, Orb. 
( ) planorbiformis, sp. nov. 
(Hormosina) chrysalis, Hausl. 
( ) transversarii, Héusl. 
T. (——) pusilla, Gein. T. 
T. (——) filum, Schm. i 
T. ( ) jurassica, Hausl. aD 
T. (prop.) constricta, Haust. Z 
T, 
ER. ) coronata, Brady. 
T. (——) squamata, J. & P. 
Further Notes on Trochammina (Ammodiscus) incerta. 
Since my first paper on the Trochammine of the Lower 
Malm appeared in this magazine careful researches in every 
successive layer of the zone have yielded thousands of perfect 
specimens, of which several not or only cursorily named in 
the above-cited notes deserve special mention. 
By the use of new methods the most fragile forms were 
obtained in considerable number, while it was formerly im- 
* Hausler, loc. cit. p. 34, pl. ii, fig. 52. 
24* 
