groove or channel along each o f its borders. It is from this resemblance to a
portion o f a fluted column, that the animal takes its specific appellation {Meg^.
laqueatus).
“ The crown w'ould resemble an irregular ellipsis widest at the anterior portion.
T he tooth consists o f a central pillar o f bone surrounded with enamel, the
former o f a dead white, the latter o f a ferruginous brown colour : the transverse
diameter is more than two-thirds le ss than its length, whilst that o f Meg'^. Jeffersonii
is only one-third le ss—the antero-posterior diameter is one-half its length in
the former, and two-thirds le ss in the latter. The proportions o f this tooth are
consequently totally at variance with that o f its kindred sp e c ie s.” [Vide Pi.
X I I . fig. 7, 8 , 9.]*
Dr. Harlan describes also two claws o f the fore-foot, a radius, humerus,
scapula, one rib, an os calcis, a metacarpal bone, certain vertebræ, a femur, and
tibia, o f the same Megalonyx; these parts o f the skeleton, together with the tooth,
which so fortunately served to establish the generic relationship of the spe cie s
with the Megalonyx o f Jefferson and Cuvier, were discovered in Big-bone-cave,
Tenessee, United States,
Dr. Harlan does not enter into the question o f the generic characters ot
Megalonyx, but it would seem that he felt them to rest not entirely on dental
modifications, for he observes that “ a minute examination o f the tooth and knee-
jo in t renders it not improbable, supposing the la st named character to be peculiar
to it, that if the whole frame should hereafter be discovered, it may even claim a
generic distinction, in which case, either A ulaxodon, or P le u r o d o n , would not be
an inappropriate name.”'f
There can be no doubt, as it appears to me, with respect to a fossil jaw
presenting teeth in the same number, and o f the same general structure, as in the
Megatherium, and with individual modifications o f form, as well marked as those
which distinguish Megatherium from Megalonyx, that the Palæontologist has no
other choice than to refer it, either as Fischer has done with Megalonyx, to a distinct
spe cie s o f the genus Megatherium, or to regard it as the type o f a subgenus distinct
from both. With reference, however, to the Pleurodon o f Dr. Harlan, after a detailed
comparison o f the cast o f the tooth on which that genus is mainly founded,
with the descriptions and figures o f the tooth o f the Megalonyx Jeffersonii, in the
“ Ossemens F o s s ile s,” they seem to differ in so sligh t a degree as to warrant only a
specific distinction, and this difference even, viewing the various proportions o f
the teeth in the same jaw o f the Megatherium, is more satisfactorily established
by the characters pointed out by Dr. Harlan in the form and proportions o f the
radius, than by those in the tooth itself.
Medical and Physical Researches, pp. 323—4.
t Loc cit. p. 330.
The nex t notice o f the Megalonyx which I have consulted, in the hope of
meeting with additional and more precise information as to its real generic characters,
is an account given by the learned Professor Doellinger,* o f some fossil bones,
collected by the accomplished travellers S p ix and Martius in the cave o f Lassa
Grande, near the Arrayal de Torracigos, in Brazil. In this collection, however, it
unfortunately happens that there are no teeth, but only a few bones of the extremities,
including some ungueal phalanges, which Professor Doellinger concludes,
from their shape, the presence o f an osseous sheath for the claw, and the form of
their articulation, to belong, without doubt, to an animal o f the Megatlierioid kind,
about the size o f an Ox. H e particularly states that they are not bones o f an
immature individual; but that they agree sufficiently with Cuvier’s descriptions
and figures o f the Megalonyx to be referred to that spe cie s o f animal (zu dieses
th ie ra r t;) and he adds, what is certainly an interesting fact, that the fossils in
question form the first o f the kind that had been discovered out o f North
America.
Subsequently to the discovery o f these bones, and o f those o f the Megalonyx
laqueatus above alluded to, the remains o f another great Edentate animal were
found in North America, and were deposited in the Lyceum at N ew Y o rk ; among
these is a portion o f the lower jaw with the whole dental series o f one side. It
is thus described b y Dr. Harlan.
“ The fragment I am now about to describe is a portion o f the dexter lower
jaw o f the Megalonyx, containing four molar t e e th ; three o f the crowns o f these
teeth are perfect, that of the anterior one is imperfect. These teeth differ considerably
from each other in shape, and increase in size from the front, the fourth
and posterior tooth being doable the size o f the first, and more compressed
laterally ; it is also vertically concave on its external aspect, and vertically convex
on its internal a spe ct; the interior or mesial surface is strongly fluted, and it
has a deep longitudinal furrow on the dermal aspect, in which respect it differs
from the tooth o f the M . laqueatus previously described by me, o f which the
dermal a spect is uniform, but to which, in all other respects, it has a close resemblance.
I suppose it therefore probable, that this last may have belonged to the
upper ]aw. The three anterior molars differ in shape and m a rk in g s: they are
vertically grooved, or fluted, on their interior and posterior aspects, a transverse
section presenting an irregular cube. The length o f the crown o f the posterior
molar is two inches : the breadth about five-tenths o f an inch : the length o f the
tooth is three inches and six -ten th s. The diameter o f the penultimate molar is
eight-tenths by seven-tenths o f an inch. The length o f this fragment o f the
jaw-bone is eight inches and four-tenths ; the height three inches and six-tenths :
the length o f the space occupied by the alveolar so ckets five inches and eight-
* Spix and Martius, Reise in Brazil, Bandii. p. 5.