XXIV. (coHtiniml).
I'ig. 2. Orycteropus.
Fig. S. Dasypus.
Fig. 4. Myrmecophaga juhata ; all one-
third nat. size.
XXV. Fig. 1 and 2. Ilnnicnis, radius and
ulna of Scelidotherium.
Fig. 3. Head of humerus.
Fig. 4. Head of radius.
Fig. 5, 6, and 7. Femur of Scelidothe-
XXVI. Fig. 1, 3, and 5. Astragalus of Megatherium.
Fig. 2, 4, and 6, Astragalus of Scelido-
themum.
XXV II. Fig. 1 and 2. Patella and head of tibia
of Scelidotherium.
Fig. 3, 4, and 5. Ungueal phalanx of
Scelidotherium.
X X V III. Fig. 1. Astragalus of iV(v;r«i7ienMm.
Fig. 2. Astragalus oi Scelidotherium.
Fig. 3—6. Astragalus of Mylodon or
Megalonyx.
X X IX . Lower jaw of Megalonyx Jeffersonii.
X X X . Fragment of the Cranium of Megatherium
Cuvieri.
X X X I. Section of the upper jaw and teeth of
the Megatherium Cuvieri.
X X X II. Fig. 1. Magnified view of structure of
molar of Megatherium.
pjjT. 2—5. Ungueal phalanx and portions
of tesselated armour of
Hoplophorus euphractus.
Fig. 6— 11. Jaws and teeth of Ctenomys
priscus.
Fig. 12. Bones of right hind-foot of a
Rodent.
Fig. 13 and 14. Fossil tooth ofa Horse.
P E E F A C E.
H i s M a j e s t y ’s ship, B ea g le , under the command o f Captain
FitzRoy, was commissioned in July, 18 3 1 , for the purpose
o f surveying the southern parts o f America, and afterwards
o f circumnavigating the world. In consequence o f Captain
FitzRoy having expressed a desire that some scientific person
should he on hoard, and having offered to give up part o f his
own accommodations, I volunteered my services ; and through
the kindness o f the hydrographer. Captain Beaufort, my appointment
received the sanction o f the Admiralty. I must here,
as on all other occasions, take the opportunity o f puhlicly
acknowledging with gratitude, the obligation under which I lie
to Captain FitzRoy, and to all the Officers on board the Beagle,
for their constant assistance in my scientific pursuits, and for
their uniform kindness to me throughout the voyage. On my
return (October, 1836) to England, I found myself in possession