HARDWICKE'S SCIENCE-GOSSIP. 



>4i 



A CHAPTER ON BRITISH FOSSIL BIRDS. 



By ARTHUR SMITH WOODWARD. 



[Continued from page 223.] 



^ ASSING on to the 

 Cainozoic forma- 

 tions, the London 

 Clay of the Eocene 

 period contains the 

 most interesting 

 relics of an avian 

 fauna. No bird- 

 remains appear to 

 have been recor ded 

 yet from the 

 Thanet sands, and 

 only very few 

 fragmentary orni- 

 tholites have been 

 met with in the 

 overlying Wool- 

 wich and Reading 

 beds. 



In the London 

 Clay of the Isle of 

 Sheppey, more or less imperfect skulls belonging to 

 four genera of birds have been discovered ; and the 

 other remains of the same class, which have been 

 described by Professor Owen, consist of a sacrum 

 from Sheppey, some wing-bones from Sheppey, a 

 sternum from Primrose Hill, London, and a sternum, 

 associated with other fragments, from Sheppey. 



The detached sacrum, though certainly that of a 

 bird, is not of any great importance, owing to the 

 fact that no idea can be obtained of the order or 

 family to which the individual, of which it formed a 

 part, belonged. The sternum from Primrose Hill, 

 likewise, cannot be relegated to any very definite 

 position, although there seems to be little doubt but 

 that it indicates the existence of a genus of wading 

 birds in early Eocene times. 



The four fragmentary crania are of the greatest 

 interest, and possess certain well-defined characters 

 which have revealed many facts regarding the ornitho- 

 logy of the South British regions, at the remote period 

 No. 227.— November 1883. 



when the London Clay was deposited. The most re- 

 markable specimen is the hinder portion of the skull 

 and mandible of a dentigerous bird, designated by 

 Professor Owen, Odonloptcryx toliapicus. 



In Odontopteryx — of which the total length of the 

 perfect skull was probably not less than 5 or 6 inches 

 —the beak is longer than the cranium, and both 

 upper and lower jaws exhibit the peculiarity of pos- 

 sessing tooth-like processes, consisting of conical, 

 sharp-pointed projections from the bone of the al- 

 veolar borders. Indeed, so remarkable is this latter 

 character that, together with one or two other pecu- 

 liarities, it might at first sight lead to doubts as to 

 whether Odontopteryx was really a bird, and not a 

 creature of the reptilian class. When, however, we 

 find that all the modifications for the characteristic 

 movements of the beak, as it is employed by birds, 

 are to be detected, and when we consider the size of 

 the orbits, the form of the condyle, and the conforma- 

 tion of the well-developed brain, it is not difficult to 

 perceive — as Professor Owen has pointed out — that 

 the interesting cranium must have belonged to one of 

 the feathered tribe. Further proof of the correctness 

 of this conclusion is to be obtained from a portion of 

 the atlas-vertebra attached to the specimen, which is 

 truly of the avian type. 



The denticulations of the jaw have a truly osseous 

 structure, and are not covered even at the extremities 

 with enamel. They are distinct processes of the bone, 

 retaining not only its microscopical structure, but 

 also certain delicate markings which characterise its 

 surface. All the denticles are not of the same size, 

 but the series of both upper and lower jaws consists 

 of smaller cones separated at intervals by solitary 

 larger ones ; they are slightly inclined forwards, and, 

 supposing that the length of the alveolar borders was 

 originally three inches, and that the " dentition" was 

 uniform throughout, there would be forty of the larger 

 cones in the complete mouth. No known living bird 

 possesses any structure analogous to that exhibited 

 in the mandibles of Odontopteryx, and even those 



