﻿34 



GEOLOGICAL MEMOIRS. 



of the tertiary or Brown-coal age. Eunotia longicornis and E. 

 Phrygia occur here as very abundant and peculiar forms ; the former 

 is already remarkable on account of its occurrence in the passat- 

 stanbe ; whilst the latter is a new species. Amphora paradoxa and 

 Discoplea Phrygia are other peculiar new forms. Fragilaria para- 

 doxa of the Jordan is present here also. 



[T. R. J.] 



The Quicksilver Mine at Almada in Spain. 



By M. WlLLKOMM. 



[Leonhard u. Bronn's N. Jahrb, f. Min. u. s. w. 1850, 4 H. p. 497 ; and Berg- 

 werksfreund, 1849, xiii. p. 72 et seq.~] 



These mining works were known to the Romans. A long, tunnel- 

 like gallery, the Socabon del Castillo, lined throughout with freestone, 

 roomy enough to admit of carts with two horses abreast, and fur- 

 nished on both sides with granite foot-ways, passes from the flat 

 valley at the southern foot of the ridge, on which Almada is built, 

 into the mine : the whole town is undermined. From this tunnel 

 many other passages are cut in the clay-slate, which is the matrix 

 of the ore, one of which opens into the Boveda de Santa Clara, a 

 dome-shaped hall, 51' high and 42' broad. Here formerly stood a 

 horse-winch for the removal of the ore. The workings reach a depth 

 of 1140'. The Cinnabar Vein, with a strike east and west, and a 

 nearly perpendicular dip of from 60° to 70°, has an almost fabulous 

 bulk. In the first storey, of which the mine has nine, the vein is 18' 

 strong, in the lowest it is 60'. The spectacle of this colossal vein of 

 ore at the working places is gorgeous, from the dark-red colour of 

 the Cinnabar, which appears sometimes earthy, sometimes in dense 

 masses, and sometimes even finely crystallized. Dispersed through 

 it are calc-spar druses, and at many places small holes and clefts filled 

 with pure quicksilver. [T. R. J.] 



On the Agreement of Pygopterus lucius with Archegosaurus 

 Dechenii. By G. Jager. 



[Leonhard u. Bronn's N. Jahrb. f. Min. u. s. w. 1850, 3 H. p. 380, and Abhandl. 

 Akad. Wissensch. Munchen, 1850, v. pp. 877-886, pi. 26.] 



The Pygopterus lucius, Agassiz *, from the Coal-formation of Saar- 

 briick, depended for its determination on a single cranium with teeth, 

 in the Stuttgard Museum. The author, having received from H. v. 

 Alberti a quite similar, but somewhat larger specimen, from the same 

 locality, is enabled to show that these crania do not belong to any 

 Fish, but to a Reptile, and indeed to the genus Archegosaurus, and 

 very probably to the species A. Dechenii, Goldfuss. 



[T. R. J.] 



* Poissons Fossiles, I. p. xxxvi, II. i. p. 10, ii. p. 78 & 162. 



