142 ON RHAMPHORHYNCHUS BUCKLANDI 
The distance between the two edges of the rami opposite the 
posterior extremity of the symphysis is +4ths of an inch, the depth 
of a ramus measured perpendicularly at the same point being 7%ths 
of an inch. The outer faces of the rami are here inclined at an 
angle of 45° to a vertical longitudinal plane; and they converge to a 
rounded edge, which forms the lower margin of the symphysis, and 
bends upwards anteriorly, so as to exhibit a slight downward con- 
vexity. In front, the symphysis ends in the base of a stout median 
process, whose continuation is unfortunately fractured. Its section is 
an elongated oval with rather sharp extremities, having its greater 
diameter about ;3,ths of an inch long and vertical. Its transverse 
lesser diameter measures 4+ of an inch. It is obvious, from what 
remains of the upper and lower contours of this beak-like process, 
that it was curved and prolonged upwards and forwards. Its walls 
are exceedingly thin, and the cavity which it contains is filled with a 
partially crystalline matrix. 
Immediately behind the base of this rostrum the ramus of the 
mandible suddenly deepens to {ths of an inch, the chief increase in 
diameter being due to the projecting edges of two large, transversely 
oval alveoli, each nearly } inch wide, which are directed forwards and 
outwards on either side. 
Behind these alveoli the jaw narrows a little, but at ths of an 
inch from their posterior boundary deepens once more to {ths of an 
inch. A second equally large alveolus, which also looks forwards, 
outwards, and upwards, occupies the posterior part of the concave 
interspace in front of this second deepening on each side. After a 
second slight contraction, the lateral margin of the jaw rises again 
opposite the symphysis, where the ramus has the dimensions given 
above. Just behind the line of the symphysis is another oval alveolus 
of the same length, with a slightly more outward and less forward 
direction. 
Three-eighths of an inch from the posterior margin of this third 
alveolus is a fourth, of about the same size; and after a similar 
interval a fifth alveolus follows,—the sinuation of the margin between 
the two last alveoli being much less marked. The interval between 
the upper edges of the two rami at the level of the last alveolus, 
which is about 14%; inch behind the posterior edge of the symphysis, 
is 14 inch. 
From the hinder margin of the last alveolus of the posterior 
extremity of the fragmentary ramus is a distance of 1} inch; 
and the distance between the fractured ends of the two rami is 
14 inch. 
