



o/Thuraramina papillata. • 263 



they belong to two species, Th.papil1ata 9 Bm(\y } and Th. hemi- 

 sphcerica, Hausl. Both make their appearance again in the 

 compact limestones of the Callovian zones, where, however, 

 they are very rare. The finest and most numerous shells of 

 Th. papillate have been collected in the sponge-beds of the 

 Lower Malm, especially in the zone of Ammonites transver- 

 sarius (Argovian I.), where the whole family Lituolida3 

 reaches its maximum development in the Jura -sic formation. 

 In a paper on the Trochamminw of this zone * I proposed to 

 divide the alternating layers of soft marls and harder marly 

 limestones into three subdivisions in the Canton Aargau. In 

 accordance with the different lithological and palseontological 

 characters, we observe certain striking differences in the distri- 

 bution and the composition of the arenaceous Foraminifera f. 

 The oldest calcareous beds, full of siliceous sponges, Brachio- 

 poda, Cephalopoda, &c, contain a rich fauna of arenaceous 

 types, among which the Thurammince are conspicuous by 

 their comparatively large size and certain peculiarities in 

 the disposition and shape of the papillae and the texture of 

 their thin walls. While these beds yielded the largest and 

 most irregular forms of a characteristic yellowish colour, the 

 younger layers contain particularly the more regular colourless 

 varieties, and the youngest argillaceous beds, C, the minute 

 more or less spherical specimens. 



These small varieties, somewhat resembling Th. albicans } 

 Brady, are unfortunately so cemented into the matrix that it 

 is almost impossible to extract perfect specimens. In the 

 younger zone of Terebratula impressa (Argovian TI.) the 

 whole genus is represented by a similar very scarce variety of 

 Th.papillata. In the compact limestones of the following zones, 

 especially in the sponge-beds of the Lower Sequanian stage, 

 the Thurammince are moderately plentiful. Towards the 

 Kimmeridge group of the Swiss Jura they disappear gradu- 

 ally ; and, so far as I could observe, only one doubtful variety 

 passes into the Lower Cretaceous beds (Neocomian I.) of the 



Cantons Vaud and Neuchatel. 



Further researches in other Jurassic countries will no doubt 

 enable us to give in a short time a more complete account of 

 the distribution of this interesting species. 



As a rule, Thurammina papillata is found in greatest 

 number and finest specimens in the beds with abundant 

 Hi/per ammince (H. vagans, Brady) . 



In comparing a great number of specimens of different ages 



* Ann. & Mag. Nat. Hist. ser. 5, vol. x. p. 49. 



t These differences and the characteristic varieties will he described ia 

 my MonogTaph of the Foraminifera of the zone of Am. transversarius. 



