213 



posed of fine, sharp, quartz-sand, with a slight admixture of clay, 

 and occasionally a tiny, silvery flake of mica. The fragments of 

 sandstone lying on the surface are usually more or less decomposed, 

 and are apt to be stained with iron oxide, which makes them very 

 hard on the outside, while sometimes the surface is covered Avitli a 

 thin layer of the same material. When unaltered the rock appears 

 to be white, or slightly reddish in color. 



The fossils most abundant in the sandstone are the Brachiopoda, 

 which are represented by twenty species belonging to the following- 

 genera: Terehratula,Vitulina, Tropidoleptus, Spirifera, Crytina{?) 

 Retzia, Strcptorliynclius, CJionetes, Orfhis, Rltynclionella, and Lin- 

 gula, all of which are described in the paper of Mr. Eathbun, 

 annexed. The only other Articulates are the trilobites which are 

 represented by a beautiful Dalmania that occurs in abundance, 

 and a species of Homalonotiis, of which last only a fragment is 

 knoAvn. 



Several species of Lamellibranchs occur in the sandstone, belong- 

 ing to NucuMtes, Palaeoneilo, Grammysia (?), Edmondia, and one or 

 two other genera. The Gasteropods number about eight species, 

 representing the genera Belleroptlion, Platyceras, Holopea, Pleuroto- 

 maria and Tentaculites. A few fragments of crinoid stems have 

 been found, together with a number of obscure markings which 

 may be of plants. 







Serra of Erer6 from the North. 



This fauna has an unmistakable Devonian facies, but it is diffi- 

 cult to determine its exact equivalency. In some features, as for 

 instance in Spirifer Pedroana, Avhich closely resembles S. varicosa, 

 the fauna recalls that of the Corniferous, while in the occurrence 

 of Tropidolep)tus and VituUna it approaches the Hamilton.* 



* See conchuling remarks to Mr. Rathbiin's paper. 



