COCHLIODOUTID*. 
195 
satisfactory specimens are required to render it certain that the 
species does not pertain to Tomodus. 
Fonn. 4' Loc- Lower Carboniferous Limestone : Bristol. 
The following species have also been founded upon detached 
teeth, but there are no examples in the Collection : — 
Systrodus alatus, L. G. de Koninck, Faune Calc. Carbf. Belg, 
pt. i. (1878), p. 64, pi. V. fig. 9. — Upper Carboniferous 
Limestone; Vise, Belgium. 
Xystrodus hellidus, 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 iMondiius, St. John & Worthen, tom. cit. p. 179, pi. viii. 
fig. 1. — Keokuk Limestone ; lUinois and Iowa. 
(?) Xystrodus (?) occidentalis, 0. St. John, Proc. Amer. Phil. Soc. 
1870, p. 430, and in Hayden’s Final Rep. Geol. Surv. 
Nebraska, 1872, p. 244, pi. iv. fig. 18. — Upper Coal 
Measures ; Nebraska. 
Xystrodus parheri, J. W. Davis, Geol. Mag. [3] vol. iii. (1886), 
p. 153, figs. 3, 4. — Carboniferous Limestone ; Derbyshire. 
Xystrodus sim 2 )le.v, St. John & Worthen, tom. cit. p. 178, pi. viii. 
figs. 4, 5. — Upper Burlington Limestone; Iowa and lUiuois. 
Genus DELTODUS, Agassiz. 
[Morris & Roberts (ex Agassiz, MS.), Quart. Jourii. Geol. Soc. 
vol. xviii. 1862, p. 100 ‘.] 
Syn. Teeniodua, St. John & Worthen, Pal. Illinois, vol. vii. 188-3, p. 76 
(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 
* The name only is hero mentioned and applied to the species previously de - 
scribed and figured by M'Coy, under the name of Pceciludm suhlcevis. The type 
species being thus already well-defined in 1862 , the generic name may be 
regarded as dating from that year . 
P. 2476-7. Type specimens. 
P. 2478. A similar, but smaller dental plate. 
Eiinishillen Coll, 
EnnisTcillen CoU. 
o2 
