310 ME. T. ATTHEY ON ANTHEACOSATJETTS EUSSELLI. 



prominence between them ; this with a similar but smaller pro- 

 jection at the posterior margin of the vacuity, seen best on the 

 right side, shows where the ligament bounding the true orbit on 

 the outer side had been attached. 



The inner margin of each orbital vacuity is slightly arched, 

 the concavity looking outwards ; the outer margin is also arched, 

 and looks inwards and slightly forwards. These end posteriorly 

 in a small concavity, the inner extremity of which, coming for- 

 wards, joins the inner margin of the vacuity, forming with it 

 the posterior projection above mentioned. 



The true orbit and the rest of the vacuity are very much 

 smaller, and placed further back than in Loxomma. The eye, 

 therefore, of Anthracosaurus must have been very much less than 

 that of Loxomma ; the part of the vacuity not occupied by the 

 eye points outwards instead of forwards. 



The floors of the orbital vacuities being deficient, they appear 

 like two perforations of the cranium, the inner side of the left 

 and the outer side of the right one having portions of bone only 

 partially filling them up, Plate VI., fig. 1, 0. V. These portions 

 are parts broken off from the pterygoid bones, which, as can best 

 be seen on the under surface of the skull, Plate VII., 0. V., 

 formed originally the floors of the orbital vacuities. 



The parietal foramen is distinct ; and the channels leading to 

 the external auditory openings are also well defined, especially 

 on the left side. 



The premaxillaries are very strong bones, but of small size, 

 measuring from front to back, on the median line, on which they 

 are firmly united, only one inch. Their anterior borders, slightly 

 arched, form the rounded snout. Prom side to side, along their 

 anterior margins, they measure three inches. On each side they 

 articulate behind with a small part of the maxilla, and form the 

 anterior concave border of the nasal orifices. Between these 

 parts they are bounded entirely by the nasal bones, indenting 

 them deeply on each side of the middle line. 



The maxillaries occupy the margins of the upper jaw behind 

 the premaxillaries, and are very long, eleven inches and a half, 

 very narrow, and of small vertical extent. They articulate with 



