284 
broad, obtuse form of beak; and I confess that the general conformity of cranial struc- 
ture under the modifications illustrated in the present Memoir do not promise an 
advantage, by drawing a line which must be more or less arbitrary in whatever direc- 
tion, equivalent to the imposition of two names for such diyisions of a group of species 
so natural and closely allicd as I would at present indicate by the sole generic name 
Dinornis, 
On the Cranium of a Gigantic Bird (Dasornis' londinensis, Ow.) from the 
London Clay of Sheppey, Kent. 
The study and foregoing illustrations of the cranial structure of the recently extinct 
species of large terrestrial birds, induce me no longer to defer communicating similar 
evidence of one which passed away at a much more remote period of geological time. 
This evidence is the cranial part of the skull, which has been reduced by rough usage of 
the elements to a similar state with that of the cranium of Dinornis giganteus above 
described (p. 277). Very little of the outer table of the walls of that cavity is preserved ; 
and much of the thick pneumatic diploé is exposed, not only along the upper (parieto- 
frontal) walls, but at the back and base of the cranium. 
To this state it appears to have been brought, probably in its transport seaward by 
the mighty eocene river, prior to petrifaction in the mud with which it finally became 
enveloped, In the mass of such matrix, converted into petrified “ London clay,” of 
which geological formation the Isle of Sheppey now mainly consists, this cranium was 
gathered with other eocene fossils, and was obtained from a local collector by the 
Earl of Enniskillen, F.R.S., to whom I am indebted for the opportunity of describing 
it, and to Mr. Davies, of the Department of Geology, for first calling my attention to 
the specimen in a collection of Sheppey fossils which Lord Enniskillen had sent (for 
determination) to the British Museum. 
In size this cranium equals that of the Dinornis giganteus; its proportions are also 
dinornithic, exemplified in the great breadth, small height, and forward slope of the occi- 
put, in the flatness of the calvyarium—with all the indications, in short, of low cerebral 
development. But there are well-marked differences as compared with Dinornis. The 
occipital condyle exceeds in size by 1 line that of Dinornis robustus in both vertical and 
transverse diameters; its shape is almost the same; and it is similarly impressed along 
the middle of its upper half by a vertical groove deepening, and in the fossil slightly 
expanding, to the end. ‘This latter character is more marked in Dinornis elephantopus 
than in D. robustus; but the groove goes lower, and the hemisphere is more truncate 
above in D, elephantopus. 
The condyle in the fossil shows, under the pocket-lens, the same fine punctate diploé, 
or cellular structure, as does the condyle in Dinornis, when the thin, smooth outer coat 
' éaaos, @ thicket (in reference to the abundance of fossil fruits and other arboreal evidences associated with 
the remains of the large bird). 
