420 Revieics — W. Dames — On Archceopteryx. 



observations in a paper entitled " Jurassic Birds and their Allies " 

 (see Geol. Mag. 1881, p. 485). Lastly Herr W. Dames communi- 

 cated a paper to the Berlin Academy in July 1882, "On the Structure 

 of the Head of Archceopteryx" (see Geol. Mag. 1882, pp. 566-568). 

 We have now the satisfaction to announce the issue of Prof. 

 Dames' completed Memoir, accompanied by a large folding chromo- 

 lithographio plate giving a life-size figure of the fossil and five 

 woodcuts of parts of the structure. 



The Head (see Plate XIV.).^ 



As the head is of the first importance, we make no apology for giving 

 a detailed account of this structure from Prof. Dames's Memoir. 



The author writes : '* Since the appearance of my paper in the 

 ' Academic der Wissenschaften ' in July, 1882, ] have studied the 

 skull of the Archceopteryx more carefully and have developed the 

 teeth. The result which I have arrived at is that the entire length 

 of the skull may now be clearly seen from the articulation of the 

 jaw to the point of the beak. 



I have now also established certainly what Prof. 0. C. Marsh and 

 I had already conjectured, that there are teeth in the lower jaw as 

 well as in the upper. 



As the back portion of the skull is unfortunately not preserved, it 

 is impossible to give the exact measurement ; still it may have been 

 about 45 mm. from the occipital condyle to the point of the beak. 

 But with the exception of the injury to the back of the skull and 

 the fracture of some of the bones, caused by the compression of the 

 skull in the matrix, it is so well preserved as to allow a very fair 

 representation of it to be given. It lies upon its left side, so that the 

 right is exposed. The profile thus seen commences somewhat 

 behind the eye in a flattened curve, which continues till about the 

 middle of the antorbital vacuity. From this point it is straighter, 

 and from the nasal foramen sinks with a sharper curve to the point 

 of the beak. In the side from front to back are three large openings. 

 The most backward is the orbital foramen, sharply defined along its 

 anterior superior and posterior margin, and measuring 14 mm. in 

 diameter ; ^ the lower edge is indicated by the impression of the 

 sclerotic plates. Within this opening, near its margin, lies a ring of 

 irregular four-sided sclerotic plates, which overlap one another like 

 scales, so that nearly one-third of each plate is hidden by the next. 

 The single plates are too much broken, the edges being quite gone in 

 many places, to tell their exact number ; some fragments adhere to 

 the counterpart, those of the lower border are displaced and lie across 

 the opening for the pupil. Their number may have been twelve. 

 The open space for the eye within these plates measures 7 mm. 

 across, the length of the sirigle plates 3 — 5 mm. 



1 "We are indebted to the courtesy of Herr Prof. W. Dames for the use of the 

 illustration of the head of ArcIueojJteri/x from his Memoir. — Edit. Geol. Mag. 



2 The complete bony boundary of the orbit is rare in recent birds (the PsittacidcB 

 e.g., see Owen's Anat. Verts, vol. ii. p. 51, fig. 30). In Archceopteryx it seems to 

 have been continuous around the orbit. 



