214 
ACTINOPTEKYGHI, 
diagnosis. The total number of vertebrae is shown to be 
about 45, and of these the 21 caudals are well preserved. 
Fragments of all the fins except the anal are distinguish¬ 
able. Purchased, 1872. 
32336. Imperfect head and abdominal region, with the greater part 
of the dorsal and paired fins; Lower, Chalk, Maidstone. 
The fossil is broken across at the back of the head, and 
the opercular apparatus thus destroyed behind the pre¬ 
operculum. The cranial roof is flattened, constricted 
behind, widest at the hinder border of the orbits, and 
marked by a sharp median depression between the orbits. 
The very large froutal bones extend almost to the 
occipital border, and are smooth in the middle portion 
which passes into the interorbital depression, but are 
marked with the characteristic ornament in the outer or 
lateral portion. Anteriorly they unite in a suture with 
the short and broad, smooth mesethmoid bone; antero- 
laterally they are overlapped by the nasal bones. The 
latter elements are well preserved, each being shown to 
be antero-posteriorly elongated, almost ovate though 
pointed behind, and very conspicuously ornamented with 
radiating series of tubercles. The otic region is too 
imperfect for description, and there are no traces of 
cheek-plates; but in side-view there are recognisable 
remains of the jaws. The triangular metapterygoid is 
completely displayed, but the remainder of the pterygo¬ 
palatine arcade is obscured except at its upper border. 
The very long and slender premaxilla is imperfect in 
front, but exhibits the characteristic fine tubercular 
ornament in its hinder two thirds, while the oral margin 
still bears some of the minute teeth. The maxilla, though 
fractured, is preserved for the greater part of its length, 
underlapped more than halfway by the premaxilla; and 
its hinder third exhibits some of the large and charac¬ 
teristic spaced teeth, which are inclined with the point 
forwards. Above the hinder third of the maxilla is 
the highly ornamented supraraaxilla, antero-posteriorly 
elongated, pointed in front and rounded behind. The 
mandible is crushed at the symphysis and otherwise 
fractured, but the suture between the dentary and 
angular is distinct, and the fine tubercular ornament is 
shown to cover the lower portion of both elements, being 
