COCHLlODONTID M. 
195 
satisfactory specimens are required to render it certain that the 
species does not pertain to Tomodus. 
Form. Loc. Lower Carboniferous Limestone : Bristol. 
P. 2476-7. Type specimens. Enniskillen Coll. 
P. 2478. A similar, but smaller dental plate. Enniskillen Coll. 
The following species have also been founded upon detached 
teeth, but there are no examples in the Collection :— 
Xystrodus alatus, L. G. de Koninck, Paune Calc. Carbf. Belg. 
pt. i. (1878), p. 64, pi. v. fig. 9.—Upper Carboniferous 
Limestone; Vise, Belgium. 
Xystrodus bellulus, St. John & Worthen, Pal. Illinois, vol. vii. 
(1883), p. 183, pi. viii. fig. 3.—Lower Coal Measures ; 
Illinois. 
Xystrodus imitatus , St. John & Worthen, tom. cit. p. 180, pi. viii. 
fig. 2.—St. Louis Limestone; Missouri, Illinois, and Iowa. 
Xystrodus inconditus , St. John & Worthen, tom. cit. p. 179, pi. viii. 
fig. 1.—Keokuk Limestone ; Illinois and Iowa. 
(?) Xystrodus (?) occidentalism 0. St. John, Proc. Amer. Phil. Soc. 
1870, p. 436, and in Hayden’s Pinal Rep. Geol. Surv. 
Nebraska, 1872, p. 244, pi. iv. fig. 18.—Upper Coal 
Measures; Nebraska. 
Xystrodus parkeri , J. W. Davis, Geol. Mag. [3] vol. iii. (1886), 
p. 153, figs. 3, 4.-—Carboniferous Limestone; Derbyshire. 
Xystrodus simplex , St. John & "Worthen, tom. cit. p. 178, pi. viii. 
figs. 4, 5.—Upper Burlington Limestone; Iowa and Illinois. 
Genus BELTODUS* Agassiz. 
[Morris & Roberts (ex Agassiz, MS.), Quart. Journ. Geol. Soc. 
vol. xviii. 1862, p. 100 b] 
Syn. Tceniodus. St. John & Worthen, Pal. Illinois, vol. vii. 1883, p. 75 
(in part). 
Two posterior series of teeth represented by two separate tri¬ 
angular dental plates, marked by numerous rounded transverse 
ridges and furrows parallel to the inner border; antero- and pos- 
tero-lateral borders usually longer than the inner border, not indented. 
In each dental plate the large ridge from the outer to the inner 
1 The name only is here mentioned and applied to the species previously de¬ 
scribed and figured by M‘Coy, under the name of Pcecilodus sublcevis. The type 
species being thus already well-defined in 1862, the generic name may be 
regarded as dating from that year. 
0 2 
