1194 
SELiCHII. 
P. 1446. Four imperfect specimens ; Armagh. Egerlon Coll. 
46042. Large abraded specimen ; Boith, Ayrshire. 
Presented by liohert Craiy, Esq., 1874. 
P. 5354. Five fragments of abraded dental plates detached from 
the matrix, one being shown in PI. I. fig. 22 ; Ticknall, 
near Melbourne, S. Derbyshire. Wilson Coll. 
(ii.) “ Lower ” dental jdates. 
P. 2471-4. Four specimens figured by J. W. Davis, loo. cit., under 
the name of X. striatus ; Armagh. Ennislcillen Coll. 
P. 2475 a. Six similar specimens ; Armagh. EnnisJcdlcn Coll. 
P. 1446 a. Olio dental plate ; Armagh. Egerton Coll. 
Xystrodus verus, St. John & Worthen. 
1883. Xystrodus vents, St. John & Worthen, Pal. lllinoi.s, vol. vii. 
p. 181, pi. viii. figs.O, 7. 
Type. Detached dental plates. 
Transverse stri® upon the coronal surface largo, irregular and 
wavy, coalescing and bifurcating. “ Upper” dental plates regularly 
triangular, the inuer margin of the adult having an average measure- 
ment of about 0-009, the distance from the outer apex to tho inuer 
margin being about 0'02 ; anterior coronal elevation prominent and 
the antero-latcral border abruptly descending almost vertically from 
its summit. 
Form. ^ Loc. Chester Limestone (Lower Carboniferous) : Illinois, 
U.S.A. 
P. 2479. Two “ up])or ” dental plates detached from matrix ; horizon 
unrecorded, but probably from the Chester Limestone. 
Ennislcillen Coll. 
Xystrodus (?) egertoni, Davis. 
1883. Xystrodus eyertoni, J. W. Davis, Trans. Iloy. Dublin Soc. [2] 
vol. i. p. 4.10, pi. Iv. figs. 22, 23. 
Type. Abraded dental plates ; British Museum. 
Founded upon comparatively massive, abraded dental plates, with 
an irregular coronal surface, exhibiting little concavity, and large 
punctations only indistinctly arranged in transverse rows. More 
