36 FOSSIL ESTHERItE. 



according to Naumann, it comprises six or seven beds, of which the greatest is eighteen feet thick. 

 Naumann has described this carbonaceous shale in the first volume of his 'Lehrbuch der Geognosie,' 

 (1849, p. 701), thus — ' It varies in colour from blackish-brown to pitch-black; it is thinly and evenly 

 laminated, therefore often splitting into very thin flukes and plates, glistening on the split faces, with 

 greasy shining streak, easily shivering, somewhat soft, and so richly impregnated with bitumen that 

 it burns in the fire with a more or less brisk, but very smoky, flame, without, however, falling to ashes.' 



"Of Plant-remains in the Brandschiefer, the most abundant are Lycopodites piniformis, Schlot., and 

 Walchia filiciformis, Schlot. Remains of Fish also occur — of the genera Amblypterus, Holocanthodes, 

 Xenaeanthus, and Cephalaspis : also there are the thin shells of a Cypris, very similar to the Posidonomya 

 minuta. 



" On these shells, -which Bronn^ has also found in a very similar black shale of the Murgthal, in great 

 quantities, and which also abound in the bituminous fish-shales of Muse, near Autun (Saone-et-Loire), and 

 Bruxi^re-la-Grue (Allier), in France, a lengthy discussion has been carried on by Delahaye and Landriot, 

 as to whether they belong to the Molluscan genus Posidonomya, or to the Crustacean genus Cypris.^ 



"Without inquiring which is right in this question, we may remark that the contemporaneous occur- 

 rence of these beds at the localities mentioned, and especially their stratigraphical relations, prove their 

 identity with those of Salhausen, which moreover must be paralleled with those occurring in the Roth- 

 liegendes, between Trautenau and Hohenelbe,^ in Bohemia, and those near Oslawan, in Moravia."^ 



In the 'Bullet. Soc. Geol. Erance' (1848), 2e ser., vol. v, p. 301, Prof. Naumann 

 mentioned the occurrence of this bituminous schist at Oschatz, and its little bivalved 

 Crustacean, — the latter under the name of " Cypris," which had been also applied to it 

 (according to M. Landriot^) by A. D'Orbigny, in 1845. Michelin had referred these shells 

 to Posidonia, with some doubt, in 1836 (see 'Bullet. Soc. Geol. France,' 1836, vol. vii, 

 p. 321 ; 2e ser., vol, v, p. 305 ; and 1850, vol. vii, p. 33). 



The specimens from Saxony, in my possession, have features very similar to those above 

 described, and present the characteristics of Estheria, especially the delicate concentric 

 ridges, separated by flattened interspaces sculptured with a reticulate pattern. This is 

 faint (PI. I, fig. 27), and seems to be associated with a fine dotting. Taking one of the 

 best of the specimens as a type (and they are all so much crushed, that it is difficult to 

 find one with a trustworthy outline), this species seems to present an obliquely sub-quadrate 

 valve, with the corners rounded off; nearly equilateral, but rather less fully rounded in 

 front than behind. The umbo is situated in the anterior third of the hinge-line, which is 

 straight, long (about two thirds the length of the valve), and defined by blunt angles on 

 either end, at the downward curving of the front and hind borders respectively. 



' Leonhard und Bronn's ' Jahrb. f. Min.,' 1850, p. 577 ; where they are referred to as Posidonomya 

 tenella, Jordan. 



2 « Bullet. Soc. Geol. France,' 2e ser., 1848, vol. v, p. 304; 1849, vol. vi, pp. 90, 374; 1850, 

 vol. vii, p. 33. 



3 Girard, in Leonhard und Bronn's 'Jahrb.,' 1843, p. 757. Beyrich, 'Bericht. K. Preuss. Akad. 

 Wiss.,' 1845, p. 25. 



4 Von Hauer, ' Sitzungsbericht. K. K. Akad. Wis?.' Wien, 1850, p. 160. 



5 'Bullet. Soc. Geol. France,' 2es6r., 1849, vol. vi, p. 90. 



