52 
8ELACHII. 
angulated. Root elongated, and produced to a blunt point in the 
principal teeth. 
In the last-named character (7. lobatus bears the same relation to 
the other species of the genus that is borne by Petdlodus alleghani- 
ensis to the remaining species of its genus. 
Form. ^ Loc. Lower Carboniferous Limestone : Lanarkshire. 
Upper Carboniferous Limestone : Yorkshire, Derbyshire. 
P. 5342. Nine principal teeth, variously broken, detached from 
matrix ; Ticknall, S. Derbyshire. One specimen, oocup) - 
ing apparentl}' a median position in the mouth, is shown, 
twice nat. size, in PI. I. fig. 12. Wilson Coll. 
P. 5343. Seven very unsymmetrical lateral teeth, detached from 
matrix, with numerous obtuse denticulations ; Ticknall. 
Two specimens are shown, twice nat. size, in PI. !• 
figs. 10, 11. Wilson Coll. 
P. 3005. Five teeth, more or less broken, embedded in matrix ; 
Yoredale Rocks, Wensleydale, Yorkshire. EnnisMUen Coll. 
P. 4889. Two teeth with imperfect roots, one detached from matrix ; 
Wensleydale. Iforne Coll. 
Ctenoptychius serratus (Owen). 
184.3. Ctenojitychins serratus, li. Agas.siz, Poiss. Foss. vol. iii. pp. 173, 
.383 (name only). 
1840-4.5. Petaloilus serratus, R. Owen, Odontography, vol. i. p. 62. 
1855. Ctenoptychius serratus, P. McCoy, Brit. Palaeoz. Foss. p. 620, 
pi. 3 1 , figs. 21 -23. 
1802. Ctenopetalus serratus, Morris & Roberts, Quart. .Toum. Geol. Soc. 
vol. xviii. p. 100 (name only). 
1881. Ctenopetalus serratus, J. W. Davis, Ann. & Mag. Nat. Hist. [6] 
vol. viii. p. 420. 
1883. Ctenopetalus serratus, J. W. Davis, Trans. Roy. Dublin Soc. [2] 
vol. i. p. 612, pi. bd. figs. 6-8. 
Type. Detached tooth ; Jones Collection. 
Margin of crown acuminate in principal teeth, often gently rounded 
in others. Denticulations large, truncate, often incompletely sepa- 
rated, and crenulated at the summit. Anterior base-line of crown 
sharply curved. Root obtuse. 
This species connects the typical dentition of Ctenoptychius with 
that of Petalodus. The coronal denticulations are sometimes only 
evident at the extremities of the tooth, where the}’ are merely 
divided by short vertical folds. 
