ON SOME UPPER JURASSIC ASTRORHIZIILE AND XITTTOLIILE. 25 



2. Notes on some Upper Jurassic Astrorhizid^: and Lituolid^. 



By Dr. Eudole Hausler, F.G.S. &c. (Read November 1, 



1882.) 



[Plates II. & III] 



The latest researches on the arenaceous types of the Reticularian 

 Rhizopoda from the Swiss Jurassic formation, especially from the 

 zones of Ammonites transver sarins and A. bimammatus, have yielded 

 so many unexpected results concerning the relationship of certain 

 species and varieties with recent forms, that a few preliminary notes 

 on some important species may he of interest, as adding to the 

 knowledge of the arenaceous Foraminifera in general, and giving 

 new proofs of their wide geological range. 



If we examine the various works on Swiss Jurassic Foraminifera, 

 the small number of arenaceous forms recorded must surprise us. It 

 may to some extent be attributed to the little attention which was 

 formerly paid to many sandy species, and the imperfect knowledge 

 of the simpler forms, but probably still more to the great diffi- 

 culties attending a careful examination of the hard marls and lime- 

 stones. 



Most of the species are of comparatively small size and very 

 fragile, whereby they easily escape observation. 



The total number of determined arenaceous species is about 60 

 for the whole Swiss Jurassic formation, if we include the Textula- 

 riidce ; but, to judge from doubtful specimens and fragments, their 

 number must become considerably greater by further researches. 



These species, with an almost unlimited number of varieties, belong 

 to the following genera : — 



Placopsilina. 



Trochamrnina. 



Ammodiscus. 



Hormosina. 



Webbina. 



Thurammina. 



Textularia (Plecanium). 



Bigenerina. 



Valvulina. 



sra. 

 Astrorhiza. 

 Rhabdammina. 

 Marsipella. 

 Hyperamrnma. 

 Lituola. 

 Eeophax. 

 Haplophragmium. 

 Haplostiche. 



By far the greatest number have been found in the lowest beds of 

 the zone of Ammonites transversarius, from which all the specimens- 

 figured in this paper are taken. 



While a few species are identical with Carboniferous or Permian 

 forms (Troch. (Am.) incerta, gordialis, pusilla, Jllum), most of the 

 others most nearly approach recent deep-sea varieties, from which 

 they often differ but very little. The resemblance of the Rhizopodal 

 fauna of the Jurassic " sponge-beds " to that of the deep sea is 

 the more surprising, as many of the species have not been found 

 in the younger formations. 



As a more complete memoir on the Foraminifera of the zone of 

 Amm. transver sarins will appear next year, only a few species and 



