ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxix 



mations found in this portion of South America. This notice is 

 highly interesting, though in some respects the work of Dr. Foetterle 

 must be considered as a compilation, since he has not himself visited 

 this country. The formations which he describes are as follows : — 



1. Granite and gneiss granite, very extensively developed. 2. Gneiss 

 with mica-slate, very abundant on the east shore of Brazil. 3. Itaco- 

 lumite, partly clay-slate and partly sand. 4. Talc slate, remarkable 

 for the occurrence of diamonds. It forms some of the most extensive 

 mountains in Brazil. 5. Grauwacke formation. 6. Transition lime- 

 stone. 7. In Bolivia D'Orbigny has found slaty sandstones, with 

 remains of Cruciana, Orthis, Lingula, Calymene, Asaphiis, and Grap- 

 tolites ; these belong to the Silurian system. 8. Devonian formation, 

 consisting chiefly of quartzose sandstones, with remains of Spirifer, 

 Orthis, and Terebratula. 9. Coal formations, with several peculiar 

 European fossils, as Spirifer Pentlandi, Sp. Roissiji, and Productus 

 Villiersi. 10. Trias, consisting of variegated clays and sandstones. 

 1 1 . Chalk, the most extensive formation in South America, extending 

 from Venezuela to Tierra del Fuego. 12. A red sandstone, the po- 

 sition of which is uncertain, 13. Volcanic formations. 14. Tertiary 

 formations : fossils do not appear to be abundant in this formation, 

 and hence the difficulty of assigning it to its proper period, ib. 

 Diluvium. 



General Works. 



Amongst the many works of a more general character bearing on 

 the progress of geology which have appeared during the past year, 

 I must not omit to mention the magnificent publication of Prof. 

 Ehrenberg entitled ' Mikrogeologie.' The microscopical discoveries 

 of infusorial remains made by the author of this work during the 

 last fifteen or twenty years are too well known to require any special 

 notice on this occasion. In his present work the author professes to 

 describe the infusorial results of the microscopical examination and 

 analysis of 836 different formations derived from every quarter of the 

 globe, from almost every region between the poles and the equator, 

 and comprising the rocks of every geological formation from the ear- 

 liest periods down to the present day. The author states as one of the 

 most important geological results of his inquiries, that the arrange- 

 ment of these microscopic forms does not confirm the laws which 

 have been recognized with regard to the larger fossil organisms, which 

 regularly become more and more peculiar and divergent from existing 

 forms in proportion as we descend lower in the series. On the con- 

 trary, he finds the same genera and sometimes the same species ex- 

 tending downwards to the Carboniferous period, and possibly even 

 to the Lower Silurian and the so-called unfossiliferous sands of St. 

 Petersburgh. 



Amongst the general conclusions which have resulted from this 

 investigation, the author states that all these microscopic forms may 

 be divided into two groups. 1. Forms of fresh water and dry land. 



2. Forms of salt water and its products. Sometimes the mixture of 

 these two groups indicates the existence of ancient sestuaries and 



