EL. T. Newton—Bird-remains from Mundesley. 99 
The tibio-tarsus is chiefly remarkable for the manner in which the 
cnemial crest extends upwards beyond the femoral articular surface, 
so as to form a cnemial, or rotula-process, which occupies more 
than one-fourth of the entire length of the bone. 
The tarso-metatarsus is much compressed, and is on this account 
a most characteristic bone. The articulation for the outer toe is 
placed almost entirely behind the one for the middle toe. 
The recent species of Colymbus have a very wide range, being 
distributed throughout the Northern hemisphere. The genus— 
and indeed each species —thus exhibits in a marked degree a 
capability of adaptation to a great variety of circumstances; and as 
it is frequently found that animals possessing this plastic constitution 
extend far back in geological time, one is led to inquire, with the 
greater interest, into the past history of this genus. 
I have been unable to find any account of the Colymbus occurring 
in a fossil state in England; but the late Dr. A. Leith Adams has 
recorded the occurrence of the C. septentrionalis, among a number 
of other birds, from the Shandon Cave, Co. Waterford, Ireland 
(Trans. Roy. Irish Acad. vol. xxvi. p. 187). He hesitated however 
to admit these remains “as contemporaneous with those of the 
mammoth and the mammals found in the breccia.” The avian 
coracoid from Kirkdale cave noticed by Dr. Buckland (Relig. 
Diluv. p. 35, tab. 11, f. 28) seems to have been regarded by some 
persons as belonging to a Diver; but M. M. Hdwards (Oiseaux 
Fossiles, vol. i. p. 297) has already pointed out that this is evidently 
a mistake; and it appears, therefore, that Mr. Clement Reid’s 
specimen is the only known instance of the genus Colymbus occurring 
as a fossil in England. 
The remains of a bird from the Miocene of Allier are described 
by M. M. Edwards (loc. cit.) as Colymboides minutus. Although the 
bird is considered by that eminent naturalist to possess characters 
which justify his placing it in a separate genus, yet it was evidently 
closely allied to the Divers and Grebes. 
The bird-bones from the Cambridge Greensand, described by 
Prof. H. G. Seeley as Enalornis (Quart. Journ. Geol. Soc., vol. xxx. 
p. 496}, show a very close resemblance to the bones of Colymbus in 
several points of their structure. The arching of the femora being so 
extremely like what obtains in the latter genus, that it is difficult 
to believe they are not generically identical. The tibiae, on the other 
hand, in their much shorter rotula-process, more nearly resemble 
those of the Grebes (Podiceps). 
To what extent these Cambridge Cretaceous Birds were allied to 
the American Odontornithes, is difficult to say, for we have no 
evidence at present to show whether the British forms had teeth or 
not. The fact that the London Clay Odontopteryx had teeth, or 
something very like them, renders it highly probable that birds 
with teeth existed in this country also during Cretaceous times. 
The American toothed-bird Hesperornis certainly resembles the 
recent Divers in several points of its structure, and these resemblances 
are doubtless fully appreciated by Prof. Marsh, although he thinks 
