ASPIDORHYNCIIIDiE. 
423 
Aspidorhynchus euodus, Egerton. 
[Plate XVII. figs. 6-10.] 
1845. Aspidorhynchus euodus, Sir P. Egerton, Quart. Journ. Geol. Soc. 
yoI. i. p. 231, with outline figs. 
Type. Scales, rostrum, and presymphysial bone; unknown. 
An imperfectly known species of moderate size. Cranium rapidly 
tapering to the acute rostrum, which projects in advance of the 
mandible to an extent scarcely exceeding one-quarter of the total 
length of the cranium ; cranial bones ornamented with granulations 
and short longitudinal rugae, mandible and opercular bones almost 
smooth; presymphysial bone slender and tapering, length about three 
times as great as its maximum depth; upper laniary teeth at the 
base of the rostrum, one tooth at the dentary symphysis, and a 
single tooth at the proximal end of the presymphysial bone very 
large, the principal mandibular teeth of the dentary bone well 
spaced and of moderate size. Scales feebly rugose. 
Form. Loc. Oxfordian ; Wiltshire. 
All the following specimens were obtained from Christian 
Malford, near Chippenham :— 
40518. Imperfect head and opercular bones, with scattered scales 
and ring-vertebne. The tip of the rostrum is broken 
away, and the whole of the mandible, except the presym¬ 
physial bone, is wanting. The pterygo-quadrate arcade, 
however, and the dentigerous base of the rostrum are 
well-preserved. The skull is shown of the natural size in 
PI. XVII. fig. 6. The characteristic narrow parasphenoid 
(pas.) is exposed in the middle of the cranium and the 
nasal opening (na.) is indicated immediately in advance 
of the orbit. The quadrate bone (qu.) is fan-shaped, 
with a relatively small condyle. The ectopterygoid ( ecpt .) 
is toothless behind, where deeply expanded, and its 
slender, closely-set teeth gradually increase in size from 
behind forwards: it meets the palatine (pi.) at an 
uncertain point in front, this bone bearing a single large 
tooth posteriorly and a regular, close series of small 
teeth anteriorly. The entopterygoid (enpt.) is long and 
narrow, but imperfectly exhibited, and the metapterygoid 
is of uncertain form. Overlying the operculum of the 
left side, which is exposed from its inner face, is a long, 
narrow, laminar bone (pt.), tapering above, abruptly 
