98 E. T. Newton—Bird-remains Srom Mundesley. 
smaller, and in other respects agrees with it so exactly, that I have 
no doubt whatever of their specific identity. I have not been able 
to compare the skeleton of a black-throated diver, Colymbus arcticus ; 
but this species is said to be larger than C. septentrionalis, and con- 
sequently would not so nearly resemble the Mundesley fossil bird. 
The comparison of this specimen with the recent skeleton of 
C. septentrionalis showing such a close agreement between them, it 
will only be necessary to point out the chief peculiarities of the 
more important of these fossil bones which are characteristic of the 
Divers. The size of the specimen, as will be seen by the table of 
comparative measurements, shows that it comes nearest to the 
C. septentrionalis. 
The humerus is comparatively a long bone, with a rounded shaft 
and small proximal articular head. The pectoral ridge is strongly 
developed, and there is no pneumatic orifice. The distal end is 
widened out, and has twice the transverse extent of the shaft. 
The ulna is curved, and has its inner surface flattened, especially 
towards the distal extremity. The radius is slender and more nearly 
cylindrical, but with both ends enlarged; the outer surface of the 
distal extremity having two well-marked grooves. 
The ankylosed metacarpals are flattened, and the first one is much 
longer than is usual in birds, occupying quite one-third of the length 
of the middle or second metacarpal. 
The femur is remarkably short, has the upper surface strongly 
arched, and the ends of the bone much laterally expanded. The 
crest of the outer condyle, which plays between the tibia and fibula, 
is strongly developed. 
Measurements in millimétres of the bones of the Mundesley fossil Colymbus. 
Creatine lengen,| neste ate [Gretiet tet a aa 
(Pernih so Pose. 39°5 12°5 14°5 6°3 
Tibio-tarsus ...... 149-0 1ogOn* EG) 4°5 
Tarso-metatarsus 68:0 12°0 IL 4-0 
imerus’) 137:0 23:0 15:0 6°3 
Biadiagisy (isk) # ds | 107:0 6:0 8°5 ae 
1 OLE Bars Mua Poe 107°0 — 12°0 4:6 
Metacarpals ...... 70:0 12-0 8-0 4-0 
* Antero-posterior extent. 
Comparative measurements of different specimens of Colymbus. 
C. torquatus COE a a daa Mundesley Polueeboiiies 
(="C. glacialis.) en B. C. Fossil. ME, Bdwards. 
Meniny: Shon. vee. 59°0 Oioaieg0 | 37:0 39°5 30°0 
Tibio-tarsus ..... /. 200°0 ie 165:0 | 149-0 149°0 eae 
Tarso-metatarsus 91:0 set 70'0| 67:0 68°0 aa 
wmmerds 3.534 200°0 185-0 | 143-0 | 182°0 13770 62°0 
Radius and Ulna 160-0 109°5 | 114:°0 | 106-0 107°0 50°2 
Metacarpals ...... 107-0 An 76:0} 68:0 70:0 oe 
t Measurements given by M. M. Edwards. 
