58 Dr. R. Haeusler on the Trochamminz 
grains of sand imbedded in a whitish or ferruginous subtrans- 
parent cement. 
In the structure of the delicate shell this variety resembles 
T. incerta irreg., sometimes even T. incerta reg. The last 
chamber is sometimes straight. 
As this variety is the most constant of all Trochammine of 
the zone, and so far found only in the lower transversarius- 
Schichten, it is a characteristic fossil for this division of the 
Upper Jurassic formation. 
Distribution. In the Cephalopod-beds of Biiren, Hottwy]l, 
Boézen. Rare. 
Trochammina jurassica, sp. nov. (Pl. IV. figs. 31-40.) 
Test free, thin, composed of a regularly-constricted tube, 
with Agathistegian mode of growth. Convolutions few, em- 
bracing ; sutural lines hardly visible. Aperture small, at the 
often projected end of the tube. 
Test delicate, built up of coarse particles of sand and mi- 
nute spicules of siliceous sponges imbedded in a constantly 
ferruginous dark brown cement. 
Diameter variable. Length 0:4 millim., breadth 0°25 
millim. 
Through the coarsely arenaceous texture and the dark rusty 
cement this species forms an exception from all Jurassic T’o- 
chammine. In its general outlines it is very variable, some- 
times compressed, the convolutions lying nearly in one plane, 
sometimes almost triangular. The last chamber is often 
straight, and bears the simple rounded aperture. 
Its nearest relations are undoubtedly the Milola-like T. 
milioloides, J.. P. & Kirkby *, and 7. Robertsoni, Br. + 
In the relative position of the last convolutions the variable 
shells of 7. jurassica imitate some Quinqueloculine, as Miliola 
seminulum, L., Q. Chemnitziana, O., Y. Buchiana, O. 
True Miliole are very rare in the beds in which T. ju- 
rassica is most abundant, except an elongated variety of 
Spiroloculina which occurs in many other horizons, chiefly in 
the hard limestones with Rhynchonella varians of the Batho- 
nian series. It is possibly the same form which Kiibler and 
Zwingli described as Ophthalmidium birmenstorfense from the 
same beds. Near Moénthal I collected casts and fragments of 
another species of Spiroloculina in the same beds with T. 
Jurassica. 
Rotaline TZrochammine with helicoid septate shells are 
* Jones, Parker, & Kirkby, Joc. cit. p. 890, pl. xii. figs, 9-14; Brady, 
loc, cit. p. 79, pl. ii. figs. 11-15. 
+ Brady, loc. cit. p. 80, pl. iii. figs. 6, 7. 
