28 
ICHTHYOTOMI. 
Genus PICRENODUSj Romanowskyh 
[Bull. Soc. Imp. Nat. Moscou, vol. xxvi. no. 1, 1853, p. 407.] 
Syn. Carcharopsis, L. Agassiz, Poiss. Foss. vol. iii. 1843, p. 813 (unde¬ 
fined) ; J. W. Davis, Trans. Roy. Dublin Soc. [2] vol. i. 1883, 
p. 381. 
Pristicladodus, F. McCoy, Brit. Palaeoz. Foss. 1855, p. 642. 
Crown of tooth relatively large, thick, and conical, but much 
compressed, with the two cutting-edges coarsely denticulated : 
lateral cones absent, or not more than two on each side. Base 
expanded at right angles to the crown posteriorly, thick, subsemi¬ 
circular in shape. 
Both the specimens to which Agassiz gave the name of Carcha- 
ropsis being contained in the Enniskillen Collection and mentioned 
below, it can be determined definitely that they are generically 
identical with the teeth described by Romanowsky as Dicrenodus 
and by McCoy as Pristicladodus. The present writer has seen no 
evidence of the difference in the form of the root remarked upon 
by J. W. Davis, loc. cit. 
Dicrenodus dentate (McCoy). 
1843. Carcharopsis prototype , L. Agassiz, Poiss. Foss. vol. iii. p. 313 
(name only). 
1855. Pristicladodus dentatus, F. McCoy, Brit. Palaeoz. Foss. p. 642, 
^ pi. 3 Gr. fig. 2. 
1883. Pristicladodus dentatus, J. W. Davis, Trans. Roy. Dublin Soc. 
[2] vol. i. p. 384, pi. xlix. fig. 22. 
1883. Carcharopsis colei, J. W. Davis, Trans. Roy. Dublin Soc. [2] 
vol. i. p. 383, pi. xlix. fig. 26. 
1884. Pristicladodus dentatus , J. W. Davis, Quart. Journ. Geol. Soc. 
vol. xl. p. 620, pi. xxvii. fig. 4. 
1888. Pristicladodus dentatus, R. H. Traquair, Geol. Mag. [3J vol. v. 
p. 103. 
Type. Detached tooth. 
Denticulations of coronal margin large, well-defined, abruptly 
truncated ; no lateral cones. 
Form. Sj' Log. Lower Carboniferous Limestone : Armagh, Ireland.* 
Upper Carboniferous Limestone : Ayrshire, Scotland ; Yorkshire, 
Derbyshire, England. 
L46044. Imperfect tooth ; Beith, Ayrshire. 
Presented by Robert Craig , Esq., 1874. 
The identity of this genus with Chilodus, Giebel (Fauna Torw. vol. i. 1847, 
p. 352), asserted by (Rebel and Heintz (Zeitschr. gesammt. Raturw. 1854, p. 77), 
must be regarded as very doubtful. 
/AA 'e ,/»2-43. 
