442 PROF. H. GOYIEE SEELE1" ON THE 



parallel to the alveolar border ; it is horizontal and somewhat ex- 

 panded. Passing backward, this surface becomes concave in length 

 by ascending a little way up the nasal process. It is divided by a 

 remarkable longitudinal groove (which originates within half an inch 

 of the anterior end of the bone) into two unequal parts (figs. 1 & 4, e). 

 The larger inner part widens considerably in front, and is nearly en- 

 closed a little further backward, where it terminates 1^ inch from the 

 palate and 1 j inch from the anterior end of the bone in a smaller 

 canal directed backward, upward, and outward. 



The larger anterior groove appears to correspond with the infra- 

 orbital canal of the second division of the fifth nerve, which seems 

 to reappear on the inner side of the bone and to be prolonged 

 backward in a groove parallel to the alveolar border (fig. 2, e). The 

 external border of the groove forms a strong oblique ridge, which ends 

 behind in a tubercle. 



The nasal or frontal process of the bone rises over the middle of the 

 bone to a height of 1|- inch from the alveolar border (figs. 1, 2, & 4, c). 

 It is very thin, and extended posteriorly a little further than is indi- 

 cated by its preservation ; it is directed upward, backward, and a 

 little outward ; its front border is straight, entire, concave from before 

 backward, and rounded from within outward, and looks obliquely 

 upward and forward. The inner triangular or subtrapezoidal surface 

 of the process is smooth, concave from above downward, and slightly 

 concave from before backward. It forms 1| inch of the external 

 border of a large anterior vacuity in the skull, which looked for- 

 ward and upward, and was presumably the left narine. The outer 

 side of the process is convex in length, with a slight oblique ridge 

 running below its superior border, while below this ridge the pro- 

 cess is convex from above downward. 



The extraordinary form of this bone is no way paralleled in the 

 maxillary bone of birds, and lends no manner of countenance to 

 Prof. Huxley's morphological hypothesis of the Avian affinities of 

 Dinosaurs. It differs from Hypsilojphodon, as figured by Mr. Hulke 

 and Prof. Huxley, in the remarkable extension of the bone anterior 

 to the nasal process, and in forming the posterior narial wall, after the 

 manner of Chelonians, Lizards, and many mammals. This process 

 is, among reptiles, Lacertian ; and is also closely paralleled in the 

 maxillary bone of Hatteria, which develops a corresponding, though 

 relatively thicker, malar process posteriorly, which is similarly 

 directed backward and downward. Hatteria has a similar ascending 

 nasal process, and similarly has conspicuous dental foramina, though 

 they are differently placed. This close correspondence becomes the 

 more important when we remember how close are the resemblances 

 to Hatt&ria offered by some Dinosaurs in the base of the cranium 

 (Craterosaurus), in the pterygoid and quadrate bones (JScelidosaums), 

 and other parts of the skull. So that we may be sure that in some 

 Dinosaurs, at least, the predominant cranial affinities are Ehyncho- 

 cephalian. 



There are, however, interesting resemblances among mammals, 

 even, to the form of this maxillary bone. Thus a similar external 



