1846.] DARWIN ON THE FALKLAND ISLANDS, 267 



Crustacea. One or two species. 



MOLLUSCA. 



Cardium ambiguum. Sow. G. Tr. v. t. 24. f. 2. 



Ostrea callifera^ Lam. Sow. G. Tr. v. t. 24. f. 7. 



Chama ? 



Spondylus ? 



Pecten. Two species, and some casts of other genera of Con- 

 chifera. 



Nautilus ? 



Globulus ohtusus. Sow. G. Tr. v. t. 24. f. 10. 



CyprcEa depressa. Sow. G. Tr. v. t. 24. f. 12. 



Turhinellus hulbiformis. Sow. G. Tr. v. t. 24. f. 1 1. 



An imperfect cast of a specimen probably belonging to this spe- 

 cies. 



Seraphs ? A cast only. The species is the same as that 



obtained from Baboa Hill, and near to S. convolutus^ Min. Con. 



There are also some other casts of univalves and a Serpula, but 

 they are indeterminable. 



2. On Markings in the Hastings Sand JBeds near Hastings, sup- 

 posed to be the Footprints of Birds. By Edward Tagart, Esq., 

 F.G.S. 



This communication was in the form of a letter addressed to the 

 President, and accompanied a specimen of one of the bodies de- 

 scribed. The markings in question appear to have been observed 

 by several persons at Hastings ; but they have not been found con- 

 secutive, or having any distinct relation to one another. They are 

 of large size, the one presented to the Society measuring sixteen 

 inches in length ; but there does not appear, either from this speci- 

 men or from the account communicated by the author, any decisive 

 evidence as to their origin. 



March 25, 1846. 



1. On the Geology of the Falkland Islands. By C. Darwin, Esq., 

 F.R.S., F.G.S. 



The Falkland Islands being a British colony, and the most southern 

 point at which palaeozoic fossils have hitherto been discovered, I am 

 induced to lay a short account of the geological structure of these 

 islands before the Society. They stretch from 51° to 52° 30' south, 

 and extend about 130 miles in longitude. My examination was con- 

 fined to the eastern island ; but I have received, through the kind- 

 ness of Captain Sulivan and Mr. Kent, numerous specimens from 

 the western island, together with copious notes, sufficient to show 

 the almost perfect uniformity of the whole group. 



