A FOSSIL REPTILIA OF THE 
In Pliosaurus grandis the number of alveoli on each side of the upper jaw is twenty-seven 
or twenty-eight. The first pair (Pl. II, q) are terminal and approximate; the outlet of each 
measures | inch 8 lines in long diameter,which lies in the axis of the jaw : the second alveolus 
(2), with an outlet 1 inch 9 lines in long diameter, which is transverse to the jaw’s axis, 1s 
divided by a partition (a’) of 4 lines breadth from the first : the third socket (¢) is divided by 
a partition (2’), half an inch in breadth, from the second ; its outlet is circular, and 2 inches 
in diameter: the fourth socket (a) is of similar size, and at rather less distance from the third: 
the fifth socket (¢) is less in transverse diameter than the third, but is equal in fore-and-aft 
diameter to the fourth, from which it stands 9 hnes apart. These five pairs of alveoli are in 
the premaxillary bones, and occupy the whole of their alveolar extent. An interval of rather 
more than 2 inches intervenes between the last premaxillary and the first maxillary 
alveolus, which is the sixth of the series; and this interval is traversed obliquely by the 
maxillo-premaxillary suture (Pl. I, 22). The maxillary alveoli have partition walls of 
about 4 lines in thickness at their free border ; but these become thinner as the teeth 
decrease in size in the hinder third part of the series. The alveoli increase in size from 
the first to the fourth maxillary tooth (ninth of the dental series); the longest diameter of 
the aperture of this socket is 3 inches: thence the alveoli gradually decrease in size to a 
diameter of half an inch. The form of the alveolar aperture is, for the most part, a full 
oval, nearly circular, with the long diameter inclining more or less transversely. 
The margins of the larger maxillary alveoli are the most prominent. The entire 
alveolar series describes longitudinally and horizontally a gently undulated course (PI. J, 
fig. 1), the premaxillary series forming a slight convexity, and the larger maxillary alveoli a 
similar convexity, outward. Longitudinally and vertically (PI. I, fig. 2) the alveolar border 
is almost straight as far as the seventeenth tooth, and then gently bends upward to the end 
of the series. A groove, deepening imto fossee answering in number to the alveoli, 
extends along the inner side of each premaxillary series (PI. I, az). This groove is 
interrupted at the diastema between the premaxillary and maxillary alveoli: it recom- 
mences at the inner side of the maxillary series (Pl. II, »), also deepening into pits 
opposite the inner and back part of the alveoli, and continues, though feebly indicated, 
along the hinder third of the alveolar series. 
The bony palate is entire, save at the palato-nares (Pl. II, », ,); but on the inner 
side of the twelfth socket, counting backward, on each side, there is a nervo-vascular 
foramen terminating a canal in the upper jaw, directed obliquely downward and forward : 
the foramen is elliptical, an inch in diameter; a shallow channel extends a few inches in 
advance of its outlet, and three or four similar but smaller foramina succeed each other 
anteriorly near the inner wall of the internal alveolar groove, leading to a linear channel 
7 inches long, which, with its fellow on the opposite side, defines the base of a median 
longitudinal ridge of the bony palate between the first three pairs of maxillary alveoli, 
which ridge (fig. 1, 21) is transversely convex, and about an inch in breadth. As the 
bony palate expands in breadth, behind the nervo-vascular foramina, it presents trans- 
