18 GEOLOGICAL MEMOIRS. 



from Herr v. Strombeck's work, and is derived from a shaft sunk to 

 the brown coal about half a mile to the west of Helmstadt. 



ft. in. 



(a) Soil 6 5 



(b) Gravel 3 1 



(c) Green sand 30 8 



{d) Green clay with sand 28 4 



(e) Grey calcareous sandstone 4 2 



(/) Green marly sand 11 8 



(g) Grey clayey sand with iron pyrites .... 10 10 



(h) Brown coal . .* 20 



giving a total thickness of 95 feet 2 inches above the brown coal. 

 The fossils occur chiefly in bed /, except a few in e, but these are- 

 identically the same as in /. The hard stone e is also petrogra- 

 phically the same as that which occiu's sometimes in single blocks, 

 sometimes in tabular masses near Lattorf, Calbe, Eggersdorf, Neu- 

 Gottersleben, Aschersleben, Wolmirsleben, &c., with typical Lower 

 Oligocene fossils. 



After describing the extent of the Brown Coal beds from Helm- 

 stadt to Westeregeln, &c., he refers to some grey-yellow clay beds 

 south of Helmstadt, which from their fossil contents, Cassis coronata, 

 Desh., Crassatella Woodli, v. Koenen, Pecten corneus, Sow., Isocardia 

 multicostata, Nyst., Cardita latisulca, Nyst., Ostrea Qaeteletii, Nyst., 

 arid Ostrea ventilabrum, Goldf., must also be considered as Lower 

 Oligocene. The author then endeavours to correct the errors in the 

 nomenclature adopted by Prof. Giebel in his ' Eauna der Braunkohlen 

 Formation von Lattorf,' owing to his want of proper means of com- 

 paring the Lattorf fossils with those of other localities ; and he adds 

 corrected lists of the fossils published on the four plates of Prof. 

 Giebel's work, and warns geologists against the too hasty adoption of 

 Giebel's names, and defends Mr. Edwards against the unfair charges 

 and attacks brought ag-ainst him by Prof. Giebel. 



Herr v. Koenen then proceeds to give a full and critical description 

 of the 122 species (omitting five species of corals) which have been 

 found at Helmstadt, pointing out their analogues or identical forms 

 in other districts, and showing where the same species occur in other 

 Oligocene formations, or in older or younger beds ; amongst these 

 are seven species of Oancellaria, 13 of Fasus, 4 of Conus, 22 of 

 PUurotoma, 5 of Valuta, 4 of Leda. This is followed by a tabular 

 statement of the whole Molluscous fauna of Helmstadt, from which 

 he deduces the following conclusions. " If we deduct from these 

 128 species the diowhiivl Nautilus imperialis, Sow., and the 17 species 

 hitherto peculiar to Helmstadt, we have a remainder of 110 species, 

 of which 100 are known to occur in other Lower Oligocene localities, 

 whilst only 31 are known as Upper Eocene and 30 as Middle Eocene 

 fossils. There can therefore be no doubt that the beds of Helm- 

 stadt are also Lower Oligocene, the more so as of these 100 species 

 59 occur only in the other Lower Oligocene, or in younger beds, but 

 not in older ones. The number of species which otherwise occur 

 only in the Middle Eocene, but not in the Upper Eocene, is only 

 four, namely Cancellaria subangulosa, Wood, var. rotundata^ 



