8 
ICHTHYOTOMI. 
Pieuracanthns arcuatus, Newberry. 
1856. Fleur acanthus arcuatus, J. S. Newberry, Proc. Acad. Nat. ScL 
Pbilad. p. 100. 
1873. Orihacanthus arcuatus , J. S. Newberry, Pep. Geol. Surv. Ohio, 
yol. i. pt. ii. p. 332, pi. xl. fig. 4. 
Type. Spine. 
Spine (so far as known) not more than 0*15 m. in length, slightly 
arched, rounded in section, but flattened posteriorly. Denticles 
small, but very robust, numerous, and closely arranged in series 
along each margin of the posterior flattened area. 
Form. Sf Log. Coal-Measures : Ohio, TJ.S.A. 
P. 1734. Impression of spine in shale ; Linton. Egerton Coll . 
P. 5443. A similar fossil; Linton. Enniskillen Coll. 
Pleurae an thus cylindricus (Agassiz). 
1843. Orthacanthus cylindricus, L. Agassiz, Poiss. Foss, vol.iii. pi. 45. 
figs. .7-9. 
1873. Ortliocanthus, T. P. Barkas, Coal Meas. Palseont. p. 20, figs. 39-42. 
1875. Orthacanthus cylindricus , J. Ward, [Proc.] North Staffs. Nat. 
Field-Club, p. 217. 
(P) 1879. Phricacanthus biserialis , J. W. Davis, Quart. Journ. Geol. Soc, 
vol. xxxv. p. 186, pi. x. figs. 16, 17. 
1880. Lophacanthus taylori, T. Stock, Ann. Mag. Nat. Hist. [5] vol. v. 
p. 217, woodc. 
1880. Pleuracantlius cylindricus, J. W. Davis, Quart. Journ. Geol. Soc. 
vol. xxxvi. p. 331, woodc. 
(?) 1881. Anodontacanthus acutus, J. W. Davis, loc. cit. vol. xxxvii. 
p. 428, pi. xxii. fig. 10. 
1888. Pleuracantlius ( Orthacanthus ) cylindricus, It. H. Traquair, Geol. 
Mag. [3] vol. v. p. 101. 
Type. Spine. 
Spine of adult fish attaining a maximum length of about 05 m., 
straight, or slightly arched towards the apex, and cylindrical in 
section. Denticles robust, pointed, arranged in double series upon 
the posterior aspect. 
Form, df Loc. Coal-Measures: Scotch Coalfield; Northumberland, 
Yorkshire, Lancashire, Staffordshire. 
P. 1735. Spine, 16 inches (0*4 m.) in length; probably from Dal¬ 
keith, near Edinburgh. Egerton Coll. 
P. 3175. An equally large specimen, more abraded; Dalkeith. 
Enniskillen Coll. 
P. 3176. Abraded fragment of small spine ; Low-moor, Yorkshire. 
Enniskillen Coll , 
