316 Bibliographical Notices. 



■were probably drifted to this spot in an entire state. One of the 

 skeletons thus placed was encrusted with scrpulae and corallines, 

 which would indicate that it had been for some time before its en- 

 tombment in the deposit, remaining in the waters which then co- 

 vered the bay. Among the shells which were found with these re- 

 mains, twelve species are absolutely identical with existing species; 

 four more are perhaps so, the doubt arising from the imperfect con- 

 dition of the specimens ; and of the remaining seven, four are very 

 minute and one extremely imperfect. The conclusion arrived at re- 

 garding this deposit is nearly similar to that relating to the first. The 

 streams, inferior to the Plata, acting together with the currents of a 

 large bay, drifted the remains of the animals towards a point where 

 sand and shingle were accumulating ; " the whole area has since been 

 elevated ; the estuary and mud of the former ruins have been con- 

 verted into wide and level plains ; and the shoals of the ancient 

 Bahia Blanca now form low headlands on the present coast." 



The third locality is in lat. 49° 15', on the coast of Southern Pata- 

 gonia, Port St. Julian. The tertiary plains of that country are mo- 

 delled into a succession of broad and level terraces, which abut one 

 above the other. The whole surface is thickly covered by a bed of 

 gravel composed of various kinds of porphyries. Tbe lower part 

 consists of several varieties of sandstone, and contains many fossil 

 shells, the greater number of which are not found in a living state. 

 The south side of Fort St. Julian is formed by a strip of narrow land 

 nearly a hundred feet in height, and on its surface existing species 

 of littoral shells are abundantly scattered. The gravel is there co- 

 vered by a thin but irregular bed of sandy or loamy soil, which like- 

 wise fills up hollows or channels worn through it. In the longest of 

 these channels the remains of the single fossil quadruped (Macrau- 

 chenia patachonica) was found imbedded. And Mr. Darwin suggests, 

 that as the Guanaco, the only large animal now inhabiting the plains 

 of Patagonia, often wanders over the extensive flats which are left 

 dry at the head of the harbour during ebb tide, we may imagine 

 that the fossil animal, whilst in like manner crossing the ancient bay, 

 fell into one of the muddy creeks and was there buried. In sum- 

 ming up the whole information collected regarding these deposits, 

 it is considered that there is strong evidence against admitting the 

 theory of a period of overwhelming violence by which these remains 

 were brought to their present state. 



The first number, besides the interesting introductory remarks by 

 Mr. Darwin, is nearly entirely occupied with the description of a 

 single gigantic quadruped, of which the cranium was discovered in 



