COCHLIODONTlDiE. 
211 
Dental plate extremely elongated antero-posteriorly ; hinder tumid 
portion passing gradually into the anterior flattened portion ; the 
latter portion longer than the former, and crossed by a small, faint, 
very oblique ridge. 
This is supposed to he the upper dental plate of Ddtoj)tychius 
acutus by St. John and Worthen h 
Form. hoc. Lower Carheniferous Limestone : Armagh, Ireland. 
P. 2419-20. Type specimens. EnnisMllen Coll. 
P. 2421. Thirty similar dental plates, the largest having an antero- 
posterior measurement of 0-053. Enniskillen. Coll. 
P. 1401. Four similar specimens. Ejerton Coll. 
28729. Two imperfect dental plates. Purchased, 1853. 
A small variety, not distinctly separable from Slreblodus colei upon 
present evidence, appears to bo indicated by the following speci- 
mens : — 
P. 4905. Two dental plates, one figured, of the natural size, in 
Ph VI. fig. 25 ; Yoredalo Rocks (Upper Carboniferous 
Limestone), Wensleydale, Yorkshire. Horne Coll. 
P. 5349. Four portions of dental plates, somewhat larger ; Upper 
Carboniferous Limestone, Ticknall, near Melbourne, S. 
Derbyshire. Wilson Coll. 
Streblodus egertoni, Davis. 
1862. Streblodus egcHoni, Morris & Roberts, Quart. Journ. Geol. Soc. 
vol. xviii. p. 101 (name only). 
1883. Streblodus egertoni, J. W. Davis, Trans. Roy. Dublin Soc. [2J vol. i. 
p. 426, pi. liii. figs. 7, 8. 
Type. Detached dental plates ; British Museum. 
A comparatively small species, the antero-posterior measurement 
of the largest known dental plate being 0-014. Hinder tumid por- 
tion of plate sharply separated by an abrupt elevation from the 
anterior portion, and about equal to it in extent ; anterior portion 
flattened, only crossed by one small angulated ridge, near to and 
parallel with the antero-lateral margin. 
Form. ^ Loc. Lower Carboniferous Limestone : Bristol. 
P. 2422-3. Type specimens. Enniskillen Coll. 
20575. Similar dental plate. Purchased, 1845. 
p 2 
' Pal. Uinois, vol. vii. p. 92. 
