from the typical form ; the inner ridge-like condyle is extended in the antero-posterior diameter, and rests
in a corresponding groove on the articular element of the lower jaw ; while the flattened ppper border of thq
thick and elevated outer wall of the latter, plays on a trochlear groove, extending externally along the
posterior moiety of the base of the condyle. This ginglymoid joint permits the protrusion and retraction of
the lower jaw, as in Parrots, for the purpose of unhusking fruit or seeds; the tympanic in theDidtmculw,
however, is readily distinguished from that in Parrots, by the double mastoid condyle.
The lower jaw varies in strength in the same ratio as the upper; it js more or less curved in the
different genera, and to the greatest extent in. the slender-billed species, in which the beak is^arched downwards
anteriorly. The dentay element is equal in length to the upper mandible; the posterior segment is
much inflated in Geoplapa ; and in all has a triangular digastric facet, which in Diimimlw slopes very
obliquely forwards and inwards, but in Geoplwpa has nearly the-.same shape as in the'Dodo ; the external
angular plate is not developed in the lesser Pigeons, The form of the articular surface necessarily varies
with that of the coadapted aspect of the tympanic ; the coronoid process is strongly developed in Kdtmeu-
Im and Treron. The vacuity between the angular, surangular, and dentary elements, is present in Gecphaps
and Grnru, as in the Dodo,; hut is obliterated in Biàmailm and Treron. The separation of the opercular
element in the Dodo, indicates the incomplete development of the individual, and [ijè occurs in the same
condition in the specimen of Geopliaps figured ; but in the huge inert Dodo, it may remain unanchylosed
longer than in the more active and volatile forms. The symphysis is broad and depressed in Gwpfofps, but
is more, acute and ascending in Treron, as in the Dodo;
In Didimmlus, the dentary element is very strong, and the core is armed, on each side, with two small
crenations, supporting corresponding teeth-like processes of the gnathotheca, as,in the Odowtqplibrim among
the Baaorea ; and the .symphysis is truncate anteriorly as in Parrots, the homy sheath covering the apex
being abraded, in the specimen examined, so as to expose the cutis. ■
It is affirmed that this bird lives on bulbous roots.; it may also live on hard-coated fruits and seeds, as
suggested by Mr. Gould ; the form of the articular surfaces of the tympanic and of the lower jaw,, indicates,
the habitual employment of the lower mandible for decorticating roots, or unlmsldng fruits and seeds, after
they have been crushed between the powerful jaws, the lower assisting especially by its dental armature ;
the depth of the impressions for the insertion of the masticatory muscles attests the strength qf these actions.
The preceding details, accompanying the unrivalled lithographs of the skull of the Dodo
(Plates VIII, IX, IX*), from the pencil of my esteemed friend Mr. Pord, (to whom I beg to
return my sincere thanks,) will, I trust, be sufficient to remove any doubt regarding the
Columbine affinities of that extinct form ; the additional evidence furnished by iksfooi remains
to be examined.
The evidence regarding the affinities-of a newly discovered or extinct bird, deducible
from the form and minute configuration of the metatarsus, is second in value only to that
furnished by the s k iS H
The metatarsus, like the head, preserves, notwithstanding such variations as occur in the
different genera and species of a common group, certain family characteristics, which are
permanent ; and which it is the province of the anatomist to eliminate, irrespective of
absolute size.
The . importance of this enquiry to the ornithologist, has led t,o its investigation in a
general manner by Kessler,1 whose, researches will, I trust, be published by the Ray Society.
1 Bulletin de la Société Impériale des Naturalistes de Moscou. Année 1841.
The variation in shape of the small posterior or accessory metatarsus, which supports
the hind toe, has hitherto been almost overlooked as a guide to classification, and farther
observations are necessary to point out its real value; in the Columbidce, the form of this bone
is characteristic, and readily distinguishable from that of the corresponding element in the
JRasores; although in some other respects, these orders closely approximate.
The number and relative length of the toes, the form and proportion of the constituent
phalanges, and especially of the ungual segment, are also important elements for indicating
the habits of birds, both as to progression and prehension. Although the Columbidce are
typically a perching group, still some of its members, as the Ground Pigeons (Gourince), seek
their food chiefly,, if not exclusively, on the ground, and require a corresponding adaptation in
the form of the foot; which is not effected by a change in the shape of the metatarsi, or in
the relative level of their trochlear extremities, in other words, by the assumption of the
strictly ambulatory form of the foot, as in the Basores and Grallce; but chiefly by the
abbreviation of the phalanges of the outer toe, which thus becomes shorter than the inner.
The same change takes place in the Dodo, which is a terrestrial representative of the
Treronine group, just as the Geophaps is a less terrestrial member of the ordinary Columbine
subtype.
The decayed and mutilated integuments were carefully removed from the remaining left
foot of Tradescant’s specimen by Dr. Kidd, the learned Professor of Anatomy and Medicine
in the University of Oxford; and we are thus enabled to test the validity of the deduction
arrived at from the study of the head, and vice versa.
The opinion advanced by Professor Owen, after an examination of this interesting osseous
relic, has been already mentioned; it is evidently based merely on the absolute size of the
metatarsus, and the figures which he has furnished of its supposed affine, will serve for its
refutation, while those given in Plate XI., will enable the reader to judge of the accuracy of
Mr. Strickland’s observations.
By authors, the principal metatarsus of birds is very generally termed the tarso-metatarsus,
but improperly, as we have no evidence of the development at any period of the tarsal
segment of the limb, or of its fusion with the three elements which coalesce to constitute the
metatarsal bone; what has been regarded by some as the tarsal element, is simply the
disjunct proximal epiphysis of the metatarsus.
The metatarsus of the Dodo (Plate XI, Fig. 1-6), which is five inches two lines and a half
long,.equals or exceeds in size that of the largest Raptorial bird, and is much greater than that
of any of the known Basores; in general form and proportions, it resembles most closely the
corresponding bone in Pigeons, especially in the shorter-limbed arboreal species, as the Treron.
The leading resemblances have already been stated,1 and an examination of the figures
(Plate XI.) will enable the general reader to verify them.
The great strength of this bone in Pigeons is remarkable, and the extended periphery
is required to give an increase of surface, for the attachment of the powerful inter-osseous
1 Part I. Chap. 1. p. 44.