174 
8ELACHII. 
dental plates with little or no lateral expansion; posterior dental 
plates with large more or less unsymmetrieal lateral “ wings/’ 
broadest in the middle, diminishing to the outer and inner margin. 
The dental plates vary considerably in form, but they are asso¬ 
ciated iu such a manner that, as already suggested by Ward and AY. J. 
Barkas, it seems probable that they pertain to a single species. A 
small jaw is described by AY. J. Barkas indicating the presence of 
about three dental plates in each ramus, the anterior being rela¬ 
tively narrower than the posterior; a portion of a fish is made 
known by Hancock and Atthey, displaying about a dozen dental 
plates in the mouth, fine shagreen, and a dorsal fin-spine; and 
several varieties of the narrow plates, with dorsal spines, are de¬ 
scribed and figured by J. AY. Davis. The tooth figured by Salter as 
Poecilodus (?) sp. is evidently a much abraded specimen. 
Form. Loc. Coal Measures : North and South AYales, Stafford¬ 
shire, Yorkshire, Northumberland, and the Scotch Coalfield. 
P. 1416. Small imperfect dental plate, with broad lateral “wings,” 
strongly furrowed; Buabon, X. AYales. This fossil bears 
Agassiz’s MS. label, “ Pleuroclus affinis” and was intended 
to he described and figured as the type of the genus and 
species. Egerton Coll. 
P. 5162. Three narrow dental plates resembling the one figured by 
Ward (Joe. cit.) under the name of P. rcinkinii ; Longton, 
N. Staffordshire. Purchased , 1885. 
P. 1415. Eight dental plates, variously abraded, mostly of the 
narrow form figured by J. AY. Davis (Joe. cit.), but one of 
the broader type, and some smaller ; Bone-bed of Betterbed 
Coal (Lower Coal Measures), Lowmoor, near Halifax, 
Yorkshire. Egerton Coll. 
P. 2481. Eight similar specimens, one of very large size (long axis 
measuring 0-02), from the same locality. 
Enniskillen Coll. 
21422. Twenty examples, variously abraded, with lateral “ wings ” 
well developed ; Carluke, Lanarkshire. Purchased , 1847. 
21975. Eight narrow dental plates, one showing a tendency towards 
division into teeth very similar to those of Helodus simplex ; 
Carluke. Purchased, 184S. 
33300. Two specimens ; Carluke. 
Purchased, 1858. 
