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THE GEOLOGIST. 



like the fossils of Archseocidaris to which I shall presently allude. This 

 specimen appears to have been stripped of its spines before being buried 

 in the sand. I have, however, found in the same bed, and near the same 

 place, a few detached plates and the casts of what appear to be spines. I 

 also find traces of large plates in some of the friable shales near it. The 

 fossils associated with this specimen are not numerous. I have sent up a 

 good specimen of Psammodus porosus from the same bed. In the lime- 

 stone which underlies the sandstone there are a great abundance of fossils, 

 of which by far the most characteristic are remains of Archseocidaris, which 

 occur in the greatest profusion. They are found in groups of plates and 

 spines ; nearly all of these groups present more or less the same assem- 

 blage of hexagonal and pentagonal plates, the former tubercled, with nu- 

 merous spines both smooth and muricated, giving the idea that each of 

 these groups represents the remains of one or more of these animals as 

 they fell to pieces. In no case do I find among these any pentagonal 

 plates provided with tubercles like those of the cast in the sandstone ; and 

 accordingly differing, as it does, from both Palaschinus and Archseocidaris, 

 I think that there can be no doubt that it is a new addition to the Echino- 

 derms of the carboniferous period. — The paper was illustrated by a careful 

 drawing of the specimen on an enlarged scale, for which the society was 

 indebted to the kindness of Mr. Bailey, who, on being called on by the 

 President, observed, that in his opinion the fossil belonged to the genus 

 Archseocidaris, but was certainly a new species. He was led to this con- 

 clusion from the fact that the whole family of the Cidaridge presented an 

 appearance like that shown on the specimen, viz. that the plates exhibited 

 one large tubercle. In the more recent specimens all the plates were tu- 

 bercled, while in this Palaeozoic fossil the tubercles only appeared on a 

 few of them. He would only observe, in conclusion, that the society owed 

 a great deal to Mr. Harte, by whose care and diligence this fossil had been 

 discovered and laid before them, like many others which they had received 

 from the same locality within the last few years. 



Mr. Emerson Reynolds then read a short communication upon " Thalli- 

 ferous Pyrites, from Ballydehob, county Cork." He said that he had ex- 

 amined several Irish ores for this element since he had laid his last notice 

 on this subject before them in 1863, but that the present specimen was the 

 only one in which he had succeeded in discovering thallium, and here only 

 in small quantity. 



Geological Society. — April 13. — 1. " On the Geology and Mines 

 of the Nevada Territory." By Mr. W. Phipps Blake. — In describing the 

 physical features of the country, the author observed that it is an elevated 

 semi-desert region, composed of a succession of longitudinal mountain- 

 ranges with intermediate valleys and plains, the most abundant rocks 

 being metamorphic and igneous ; but Tertiary strata and Carboniferous 

 Limestone also occur. 



The author then described the hot springs, which are extended along a 

 line of fissure in a granitic rock, and parallel to the mountains, and which 

 deposit silica in an amorphous and a granular state, sulphur being also 

 seen in the cracks and cavities of the siliceous deposit. He considered 

 these phenomena to illustrate the formation of a quartz-vein in a fissure. 



Mr. Blake then gave an account of certain mineral veins in porphyry, 

 which yield sulphurets of silver (including crystals of Stephanite, but very 

 little ruby silver) and a little gold ; also galena, copper p3 r rites, iron 

 pyrites, and a little native silver, the veinstone being a friable quartz. The 



