COCHLIODONTIB^. 
197 
P. 2459. Abraded example, described and figured by J. W. Davis, 
loe. cit., as an anterior tooth of Peecihdus jowsii. 
Enniskillen Coll. 
P. 1449. Three similar teeth. Egerton Coll. 
(iii.) Inrolled variety of posterior dental plates (? lower jaw). 
P. 2441. Specimen with the narrow anteriorly-placed plate in its 
natural position, described and figured by J. W. Davis, 
loc. cit. p. 430, pi. lii. fig. 9. Enniskillen Coll. 
P. 2445-6. Twenty-five variously abraded plates. 
Enniskillen Coll, 
P. 2447. Much abraded and crashed dental plate, the type specimen 
of D. e.vpansiis, Davis, loc. cit. Enniskillen Coll. 
P. 1447-8. Seven specimens. Egerton Coll. 
Deltodus gibbus, sp. nov. 
'Type. “Lower” dental plates, shown in PI. VI. figs. 19, 20. 
A comparatively small species, the maximum transverse measure- 
ment of the supposed lower posterior dental plate being about 0‘014. 
Anterior coronal elevation extending from the outer to the inner 
margin, broad, rounded, but having a hump-backed appearaneo 
when worn, gradually passing into the narrow postcro-lateral 
fiattened portion of the plate, and immediately adjoining the antero- 
lateral margin ; inner margin strongly curved throughout the greater 
portion of its length, the rounded elevation projecting. Transverse 
ridges and furrows of the dental crown narrow, feebly marked. 
The opposing dental plates of this species are not yet certainly 
recognizable; it seems likely that they are confounded with the 
supposed upper dental plates of Deltoptychius gibherulus. 
Form. 4’ Eoe. Lower Carboniferous Limestone : Bristol. 
20575 b, P. 5859. Type specimens, readily distinguished from the 
corresponding dental plates of Z). suhlcevis by their narrow- 
ness and the prominence, obliquity, and sharplj’-bent worn 
surface of the rounded coronal elevation. 
Purchased, 1846, and History unknown. 
P. 5860. Similar specimen. History unknown. 
34980. More imperfect abraded dental plate. Purchased, 1860. 
