PSAMM ODONTIDiE. 
99 
with the lateral margins strongly crimped; posterior border straight 
or convex. 
Form. Sf Loo. Lower Carboniferous Limestone : Armagh, Ireland. 
P. 2505. Type specimen, in some respects very suggestive of a 
Cochliodont dental plate. Enniskillen Coll. 
Dimyleus woodi , J. W. Davis (ex Agassiz MS.) 2 , is founded upon 
an indeterminable broken tooth (P. 2602) from the Upper Carboni¬ 
ferous Limestone of Richmond, Yorkshire, perhaps referable to 
Copodus , perhaps Cochliodont. The published figure is misleading, 
the remains of the root extending considerably on either side of the 
fragments of the crown represented; the division between the two 
portions is evidently an accidental fracture. 
The following species of Copodus have also been described upon 
the evidence of detached teeth, but there are no examples in the 
Collection:— 
Copodus corn emus ; Rhy modus corn emus, J. W. Davis, Geol. Mag. 
[3] vol. iii. (1886), p. 155, woodc. fig. 7.—Carboniferous 
Limestone; Chapel-en-le-Frith, Derbyshire. 
Copodus van hornii , St. John & Worthen, Pal. Illinois, vol. vii. 
(1883), p. 229, pi. xx. figs. 2, 3.—St. Louis Limestone; 
Missouri, Illinois. 
Copodus pusillus, St. John & Worthen, tom. cit. p. 231, pi. xx. 
fig. 1.—Chester Limestone ; Illinois. 
Copodus variabilis ; Mylacodus variabilis , J. W. Davis, Geol. Mag. 
[3] vol. iii. (1886), p. 154, woodc. figs. 5, 6.—Carbonife¬ 
rous Limestone; Chapel-en-le Frith, Derbyshire. [? Psam- 
modus.~\ 
If specifically distinct, and rightly to be placed here, Cliaracodus 
minimus , Davis (Geol. Mag. [3] vol. iii. p. 155, woodc. fig. 8), will 
require a new specific name.-—Carboniferous Limestone ; Chapel-en- 
le-Frith. 
Genus PSAMMODUS, Agassiz. 
[Rech. Poiss. Foss. vol. iii. 1838, p. 110.] 
Syn. Homalodus, J. W. Davis, Trans. Roy. Dublin Soc. [2] vol. i. 1883, 
p. 481. 
Astrabodus, J. W. Davis, Quart. Journ. Geol. Soc. vol. xl. 1884, 
p. 629. 
Teeth quadrate, more or less elongated, rarely nearly square; 
1 Trans. Roy. Dublin Soc. [2] vol. i. (1883), p. 478, pi. lviii. fig. 24. 
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