Notice of Memoirs. — W. Dames on Archceopteryx. 567 



bounded above and in front by a very thin bone, which is a part of 

 the premaxillary, which does not reach the extremity of the skull. 

 In front of it lies another portion which is about 4mm. longer which 

 is triangular, equal-sided, and forms the end of the beak. 



This opening, which is entirely surrounded by the premaxillary, is 

 affirmed to be the nasal aperture. By its discovery the resemblance 

 of the skull to that of living birds is shown to be much greater than 

 was formerly believed. As in the bird, three apertures lie on the 

 side of the skulL The hinder one is the orbit ; the middle one is 

 surrounded by the lachrymal behind and the premaxillary and maxil- 

 lary in front and below ; while more forward is the nasal aperture, 

 entirely in the premaxillary bone. Having established this analogy 

 with living birds, the study of other parts of the skull becomes much 

 clearer. Thus the crushed portion of bone in the middle aperture is 

 seen to be the inner ascending process of the maxillary bone. And 

 a longer bone running back to the base of the skull and forward, 

 beneath the orbit, is a part of the vomer. Further, the quadrate 

 bone, though not clearly determined by its characteristic form, is 

 recognized by its position. And immediately in front of it is a 

 small bone only just projecting from the matrix which from its 

 position can only be the pterygoid. 



There is little preserved of the roof of the skull, only broken 

 fragments of the frontals, and the brain cavity filled up with cal- 

 careous spar. The back of the head is wanting. A further result 

 from clearing away the matrix is the exposure of the dentition. 

 Two small teeth standing under the middle opening were already 

 visible in the natural exposure. Besides these there are nov/ ten 

 teeth in all to be seen in the jaw. The most forward is about 2 mm. 

 from the end of the beak ; yet there are traces that one or two teeth 

 stood in advance of this, so that the dentition reached to the extremity 

 of the beak. The teeth are about one mm. long, conical, very sharp, 

 and as far as a single small place with well-preserved upper surface 

 lets one see it, shining, smooth, and without perpendicular furrows or 

 ridges. The interspace between the separate teeth is scarcely 1 mm. 

 long. Marsh considered that the teeth were limited to the pre- 

 maxillary bone, since the last occurred under the nasal opening. 

 But according to the interpretation now brought forward, the 

 aperture formerly termed nasal is the middle hole of the three on 

 the side of the skull, and it is considered that the dentition is not 

 limited to the premaxillary, but also extends to the maxillary bone, 

 or at least to its anterior part. Marsh further put forward the 

 conjecture that the teeth were placed in a groove, but the present 

 examination gives no support to that view, and it rather appears 

 that every tooth stood in its own alveolus. The lower jaw is still 

 in its natural position, i.e. in its union with the quadrate bone with 

 the upper margin lying close to the skull which incloses it. It shows 

 a postarticular process, curved behind as in the existing genus Anser. 

 The position of the lower jaw as well as the closed beak prevents 

 one from seeing whether the lower jaw contained teeth, but I think, 

 with Marsh, this was probable. Under the lower jaw lies a portion 



