A. Smith Woodward—On Athrodon, a Pycnodont Fish. 485 
series, the largest forming a principal series near the symphysial 
margin of the bone. 
The dentition of the type specimen measures 0-017 in maximum 
width, and 0:08 in length. 
Form. and Loc.—Purbeckian ; Aylesbury, Buckinghamshire. 
; 5. ATHRODON PROFUSIDENS, Cornuel, sp. 
Pycnodus profusidens, J. Cornuel, Bull. Soc. Géol. France [3] vol. v. 1887, p. 609, 
pl. xi figs. 3-6. 
Type. Splenial dentition. 
Splenial bone short and broad with closely arranged teeth of 
moderate size, mostly smooth and circular, a few with a faint apical 
pit, disposed in about 7 irregular series, the largest near the 
symphysial margin of the bone. ' 
Hach splenial dentition in the type specimen measures 0-026 in 
maximum width and 0-059 in length. 
Form and Loc.—Neocomian ; Wassy, Haute Marne. 
6. ATHRODON CRASSUS, sp. nov. Pl. XVI. Fig. 2. 
Type. Right splenial bone with abraded dentition; Woodwardian Museum, 
Cambridge. 
Splenial bone short and broad, with large, widely spaced teeth, 
mostly circular, disposed in about 4 irregular series, largest near the 
middle of the bone. 
The dentition of the type specimen measures 0:02 in maximum 
width and 0-04 in length. 
Form. and Loc.—Cambridge Greensand ; Cambridge. 
7. ATHRODON TENUIS, sp. nov. Pl. XVI. Fig. 3. 
Type. Right splenial bone; Royal Museum of Natural History, Brussels. 
Splenial bone elongated, with large closely arranged teeth, mostly 
smooth and nearly circular, disposed in about four irregular series, 
of which that next to the innermost is the largest. 
The dentition of the type specimen measures 0012 in maximum 
width and 0-027 in length. 
Form and Loc.—Lower Senonian; Lonzée, near Gembloux, 
Belgium. 
8. Arnropon, sp. Pl. XVI. Fig. 4. 
In addition to the foregoing it may be mentioned that the Wood- 
wardian. Museum, Cambridge, possesses an imperfect vomerine 
dentition from the Cambridge Greensand, which probably pertains 
to Athrodon, but appears to be too small for A. crassus. Nearly all 
the teeth seem to have exhibited an apical pit with crimped border, 
and their contour’is mainly circular. The largest teeth occur in a 
discontinuous median row, and there is evidence of three irregular 
series on each side, not forming quite symmetrical pairs. 
Probably many other examples of the dentition of this interesting 
Pyenodont genus exist in collections, and it is hoped that these brief 
notes may lead to their recognition. The writer would only add on 
