156 



most indefinitively before we can arrive in safety at any general con- 

 clusion upon so intricate a problem. 



From Colonel Silvertop we have received a description of certain 

 tertiary deposits, which in the kingdom of Murcia, in Spain, occupy 

 extensive plains, bounded by discontinuous ridges of nummulitic 

 limestone, transition rocks and mica-slate : the author divides these 

 deposits into four districts, and each of these is separately treated. 

 M. Deshayes refers their imbedded fossils to the second and third 

 deposits of tertiary formation. 



In a work on Spain, published during the past year by Captain 

 Cooke, will be found a brief account of the mines and rocks of that 

 hitherto partially examined country. 



I may also be permitted to notice among the additions which 

 have been made to our library, an excellent Memoir by M.le Che- 

 valier Albert de la Marmora, on the constitution of the Balearic 

 Islands. 



No communication has been made to us from Asia since the last 

 Anniversary. 



A paper by Mr. Cunningham describes the physical structure, and 

 to a certain extent, the geological composition of the country be- 

 tween Hunter's River and Moreton Bay, in Australia, and is accom- 

 panied by a valuable map and section and a small collection of rock 

 specimens. The additions made during the expedition referred to 

 by Mr. Cunningham are important, and the geological notices, 

 though slight, will be welcomed by future inquirers, 



Mr. Rogers, who laid before the British Association at Edinburgh 

 an able sketch of the " Geology of North America," has more re- 

 cently favoured this Society with an account of the strata situate on 

 the banks of the Misouri and Mississippi rivers, and further, in the 

 district of the Rocky Mountains. It may be said of all these papers 

 that they are in a great degree compilations, but compilations so ex- 

 ecuted are perhaps among the most valuable documents that can be 

 transmitted to us. No general views could ever be opened if every 

 author were to confine his descriptions and reasonings to those 

 minute tracts which have fallen within the sphere of his own per- 

 sonal examination. Every system and theory is necessarily founded 

 upon details industriously collected from various quarters. 



Besides these communications, we have received from America 

 recently two works, in which the same subject is treated with great 

 clearness and in considerable detail: the one entitled " Contribu- 

 tions to Geology, by Isaac Lea, accompanied by six plates of 

 Shells," of which some at least are not very accurately figured ; 

 the other " A Synopsis of the Organic Remains of the Cretaceous 

 Rock, with nineteen lithographed plates of Shells, by Dr. Morton." 

 These works, together with the papers of Mr. Conrad published 

 previously in the American Journal of Science and the Journal of 

 the Academy of Natural Sciences of Philadelphia, illustrated also 

 with lithographic plates, have rendered the upper formations of 

 the United States as intelligible as those of our own country. 



