156 Geological Society. 
try, including the highest mountains of South America, and giving 
rise to the great rivers Amazon, &c. These slates, shales, grau- 
wackes, and quartzites yield abundant fossils even up to the highest © 
point reached, 20,000 feet. ‘The problematical fossils known as 
Cruziana or Bilobites occur not only in the lower beds, but (with 
many other fossils) in the higher part of the series. 
Lastly, the differences between the sections made by M. D’Or- 
bigny, M. Pissis, and the author were pointed out, though for the 
most part difficult of explanation. D’Orbigny makes the mountain 
Illimani to be granite; it is slate according to the author. M. 
Pissis describes as carboniferous the beds in which Mr. Forbes found 
Silurian fossils,—and so on. 
* On a New Species of Macrauchenia (M. Boliviensis).” By Prof. 
By ot. Huxley. vor, wet, re. ce. 
Some bones, fully impregnated with metallic copper, which had 
been brought up from the mines of Corocoro in Bolivia were sub- 
mitted to Prof. Huxley for examination. ‘The mines referred to are 
situated on a great fault; and the bones were probably part of a 
carcass that had fallen in from the surface,—the copper-bearing 
water of the mines having mineralized them. A cervical and a 
lumbar vertebra, an astragalus, a scapula, and a tibia show com- 
plete correspondence in essential characters with those bones of the 
great Afacrauchenia Patachonica described by Prof. Owen in the 
Appendix to the ‘ Voyage of the Beagle ;’ but the relative size and 
proportions of the vertebra, the tibia, and the astragalus indicate a 
distinct species, much smaller and more slender ; and in some points 
of structure this new form (M. Boliviensis) approaches more nearly 
to the recent Auchenide than to the larger and fossil species. The 
fragments of the cranium show some peculiarities of form, but, on 
the whole, it has many resemblances to that of the Vicugna. 
Prof. Huxley pointed out that this slender and small-headed Ma- 
crauchenia may have been the highland-contemporary of the larger 
M. Patachonica ; just as now-a-days the Vicugna prefers the moun- 
tains, whilst its larger congener the Guanaco roams over the Pata- 
gonian plains. 
Lastly it was remarked that as Macrauchenia was an animal com- 
bining, to a much more marked degree than any other known recent 
or fossil mammal, the peculiarities of certain artiodactyles and perisso- 
dactyles, and yet was certainly but of postpleistocene age, it presents 
a striking exception to the commonly asserted doctrine that ‘ more 
generalized”’ organisms were confined to the ancient periods of the 
earth’s history. For similar reasons, the structure of the Macrau- 
chenia is also inimical to the idea that an extinct animal can always 
be reconstructed from a single tooth or a single bone. 
** On the Paleozoic Fossils brought by Mr. D. Forbes from Bo- 
livia.” By J. W. Salter, Esq., F.G.S. 
The Fossils of Carboniferous age brought home by Mr. Forbes 
are the well-known species described by D’Orbigny. Several are 
identical with Kuropean forms (as Productus Martini, &c.), and are 
cosmopolitan ; others are peculiar to the district (as Spirifer Condor, 
Orthis Andii, &c.). 
