367 



illustrious member of our Society, the Crown Prince of Denmark. 

 The collection of recent shells formed by His Royal Highness and 

 now in his private cabinet, — more extensive perhaps than any other 

 in Europe, — has afforded Dr. Beck the most ample facilities of com- 

 paring fossil and recent shells, and from the opportunities thus en- 

 joyed we may look, at no distant period, for results which will ma- 

 terially advance the general progress of fossil conchology.* 



Few communications have excited more interest in the Society 

 than the letters on South America addressed by Mr. Charles Darwin 

 to Professor Henslow. Mr. Darwin has devoted four years, from 

 1832 to 1835 inclusive, to the investigation of the natural history 

 and geology of South America. From the position of the tertiary 

 deposits which exist on both sides of the southern Andes, he con- 

 cludes that the primary chain must have had a great elevation an- 

 terior to the tertiary period. A transvei'se section from Rio Santa 

 Cruz to the base of the Cordilleras, and another on the Rio Negro 

 exhibit the structure of what Mr. Darwin calls the great southern 

 tertiary formations of Patagonia, which may be separated into groups 

 of distinct periods analogous to those already established in Europe. 

 The lowest group is of great extent and thickness, and in one in- 

 stance was observed to alternate with a bed of ancient lava, which 

 seemed to mark the commencement of the eruptions from the cra- 

 ters of the principal chain of the Andes. Among the shells and 

 corals, even of this lowest deposit, are some which are supposed to 

 belong to species now living in the neighbouring Pacific. Over- 

 lying this is a stratum of rolled porphyry pebbles, which the author 

 traced for 700 miles. Scattered over the whole, and at various 

 heights above the sea, from 1300 feet downwards, are recent shells 

 of littoral species of the neighbouring coast, so that every part 

 of the surface seems once to have been a shore, and Mr. Darwin 

 supposes that an upheaval to the amount of 1300 feet has been 

 owing to a succession of small elevations, like those experienced in 

 modern times in Chili. 



The principal section described is one transverse to the Andes, 

 extending from Valparaiso to Mendoza. The Cordillera consists 

 here of two separate and parallel chains, the western being com- 

 posed of stratified sedimentary rocks resting on granite. The 

 strata are violently dislocated and contorted along parallel north 

 and south lines, and become crystalline as they approach the gra- 



* Having been led to speak of cretaceous fossils, I may state that it has 

 been a question whether certain fossils found in the English chalk, and 

 called by Mr. Mantell Hippurites Mortoni, are truly referrible to the genus 

 Hippurite. When I first saw one of these fossils in the collection of Mr. 

 Robert Hudson, I conjectured that it might belong to the family of Conia 

 and Balanus ; but I regret that this opinion has been published as mine in 

 Loudon's Magazine, as it was abandoned by me as soon as I had opportu- 

 nities of minutely examining the specimens. (See Loudon's Mag., No. 58.) 

 Without being able to decide whether they are truly Hippurites, I may 

 state that I believe "them to belong to the family of Rudistes of Lamarck, 

 and that they are not allied to Conia. 



