30 GEOLOGICAL MEMOIRS. 



as they are at present known, no other fossil but RhynchoneUa pe- 

 data, often in such numbers that it forms the principal mass of the 

 rock. 



The position of these strata is not yet satisfactorily investigated : 

 as they appear at the Werflinger Wand in the midst of the Dach- 

 stein limestone district, we may provisionally place them among the 

 lias. They are of a bluish grey at the Ilohe Wand, — white and yel- 

 lowish near both Lahngang Lakes, — generally black, and the Rhyn- 

 chonellcB in them frequently silicified, near Aussee ; near Hallstadt 

 they appear of a greyish- white colour and are interrupted with brick- 

 red and yellow layers. 



The so-called Lithodendron limestones are white, and do not seem 

 to be separated from the including Dachstein-limestone by any 

 striking petrographical character, so that in future they may be 

 united with it under the designation of fossiliferous layers. They arfc 

 still unknown in the eastern portion of our x\lps, and the only loca- 

 lities for them with us are the western slope of the Loser near 

 Aussee, and the Weisse Wand near Unken. The only Brachiopods 

 they contain are Spirifer Muensteri, at both localities, and with it 

 RhynchoneUa cornigera at Unken ; besides these, they contain also 

 Plicatula intusstriata and a Pecten, which seems to be met with 

 also in the Koessen strata. According to M. Peters's investigations, 

 the black Koessen strata near Unken and Lofer underlie the limestone 

 with Megaloclon triqueter, as they do in Vorarlberg, and this white 

 limestone itself includes the Lithodendron strata; so that these three 

 formations must necessarily be combined in one principal group. 

 Other localities are mentioned in the Bavarian Voralpen ; M. Schaf- 

 hautl's w^hite oolitic limestones with Rhynch. cornigera (Leonh. u. 

 Bronn's Jahrbuch, 1853, p. 299) may possibly find their place 

 among them. All the observations at present known agree in their 

 having been constantly seen at a lower horizon than the black 

 Koessen strata. 



Certain strata discovered by M. Emmrich near Unken, and sub- 

 sequently investigated by M. Peters, but not yet sufficiently cleared up 

 as to their stratigraphical relations, show similar phsenomena ; they 

 consist of white, yellowish, or reddish limestones quite filled with 

 several species of Avicula, which are elsewhere found in the Koessen 

 strata and sometimes frequent in the lias of other countries. 



These strata deserve the particular attention of future observers, 

 as their more complete investigation may prove useful in solving 

 several still undecided questions. M. Lipoid has brought from the 

 Gois- or Schober-graben, in the Wiesthal near Adneth (one of the 

 richest localities for Koessen fossils), some black and very bituminous 

 slates, containing remains of fishes, and a large quantity of one of 

 these AviculcB, viz. Avicula contorta, Portl. Subsequent observa- 

 tions must show how far these strata are connected with the well- 

 known fish-slates of Seefeld. M. Schafliautl and the Tyrol geologists 

 have placed these bituminous slates among formations which we can 

 only recognize as the equivalents of the Koessen strata. 



The Koessen, Starhemberg, and Lithodendron or Avicula strata, 



