188 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 20. 



covery : before he directed special notice to it, the matter was only 

 incidentally mentioned, and he was doubtless quite as much unaware 

 that it had been noticed before, as Professor Calvert or myself were ; 

 my object has been to direct attention to this matter as showing the 

 great extent of country in which this singular crystal is found. The 

 observations of Mr. Strickland and myself show that it is found in 

 the Keuper Sandstone through a considerable portion of Gloucester- 

 shire, and I have noticed its frequent occurrence in Cheshire ; Pro- 

 fessor Phillips has found it in Worcestershire, and Dr. Percy in 

 Nottinghamshire. The observations of Messrs. Vanuxem and Hall 

 show the existence of a similar pseudomorph in North America, in 

 the district to the south of Lake Ontario, extending from Erie County 

 through Genesee, Monroe, and Wayne to Madison County. There, 

 however, these crystals are found in the Onondaga Salt Group, be- 

 longing to the Upper Silurian Division. 



Note on the occurrence of similar Crystals. By W. W. Smyth, 

 Esq., F.G.S. 



The presence of pseudomorphous crystals, similar to the above- 

 mentioned, in several divisions of the Trias, has long attracted notice 

 on the Continent, and has been detected at very numerous points 

 scattered over a large proportion of Northern Germany. In Leon- 

 hard and Bronn's Journal for 1847, Gutberlet has devoted an ela- 

 borate paper to the description and geological discussion of those 

 more particularly which occur in beds of variegated marls between 

 the Bunter Sandstein and the Muschelkalk. They have also been 

 described by Dr. Dunker as occurring in the Wealden of Germany ; 

 by Braun, in the marl-slate of the Zechstein near Frankeuberg ; and 

 by others, in the tertiaries of Austria and of the South of France, 



In all these different localities the " hopper-shaped " crystals (or 

 cubes with hopper-shaped impressions) are the most frequent, and 

 are the same forms of salt which are produced by gradual evaporation, 

 whether in salt-pans or on a sea-shore. The materials of which these 

 pseudomorphs are constituted vary with the composition of the adja- 

 cent rocks, and are, in different localities, marly limestone, dolomitic 

 marl, gypsum, quartz (more or less pure), sandstones of many kinds, 

 mica, and brown spar, the last two often disposed only round the 

 edges. In the first-mentioned paper, and in some by Hausmann and 

 Noggerath on the same subject, will be found much valuable and 

 suggestive matter connected with both the chemical and geological 

 aspect of the subject. 



