460 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britcan 
Psammodus rugosus—Newberry and Worthen, 1866. rxeol. Surv. of Illinois,” Vol. II., p. 108, pl. 
x1, fig. 3. 
» __porosus Mf 1866. “Ibid,” Vol. IL. p. 107, pl. xi, fig. 1. 
5 reticulatus (2) i“ Ie; FI Dorel” yo, UO), Toll wah, ies, © 
sr rugosus—Enniskillen, 1869. ‘ Alph. Cat. Type Fossil Fishes,” p. 7. 
.; inflexus ()— H. Trautschold, 1874. <“Fischreste aus dem Devon. des Gouver. 
Toula, p. 11, pl. u., fig. 12. 
- porosus—F’. Roemer, 1876. ‘ Lethcea paleoz.,” pl. xlvii., fig. 2. 
» » W. H. Baily, 1875. “Figs. of Char. Brit. Foss.,” p. 120, pl. xl., 
ine, 9), 
» 9 J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 365. 
. rugosus * “ Tbid,” 365. 
i canaliculus 3 . PS OO 
% reticulatus 5 2 » 304. 
3p porosus—L. G. de Koninck, “Fauna du Cale. Carb. de la Belgique,” p. 
41, pl. v., figs. 1-5. 
Teeth, large, thick, more or less flat ; crown irregularly subtrapezoidal or oblong 
in form, occasionally nearly rectangular, sometimes triangular. Antero-posterior 
margins sub-parallel, occasionally nearly straight, oftener concavo-convex. Convex 
or anterior margin shortest. One of the lateral margins generally straight, the 
other oblique, forming a more or less obtuse angle with the anterior margin, and 
with the posterior margin extending backwards so as to form an acutely projecting 
angle. Coronal surface hollowed in the middle, raised towards each lateral margin ; 
or the central portion is raised or convex, in all probability indicating opposing 
teeth. Entire surface covered with close sinuous ridges, roughly parallel with the 
antero-posterior margins; in worn examples the wrinkles or ridges have been 
rubbed down, either over a part or the whole of the surface, where it exhibits a 
smooth, uniformly, and coarsely granulo-punctate surface, formed by the superficial 
exposure of the openings of the medullary tubes: Root of the tooth varies in 
thickness, usually inbevelled from the crown, occasionally inbevelled in front and 
on each side, whilst the posterior margin projects in a proportionate degree. 
M. de Koninck (Fauna du Calcaire Carbonifére de la Belgique, p. 42) considers 
that Psammodus porosus should be retained as the type, and describes the teeth 
under that name; on the other hand, Prof. M‘Coy describes the specimens. under. 
the title Psammodus rugosus, and as the unworn teeth all exhibit the characters 
of the surface which led Prof. Agassiz to consider the species separate from P. 
_porosus, and the distinguishing characteristics of the latter are due to the grinding 
action in using the teeth, it appears that the specific name selected by Prof. M‘Coy 
should be retained. It has also precedence in the old Catalogue of the Bristol 
* Museum in which the teeth are styled Dens tritor rugosus. & 
The oblong form, in which the antero-posterior diameter greatly exceeds that 
between the sides of the teeth, described by Prof. M‘Coy as a separate species 
Psammodus canaliculatus, must also be zincluded in the species P. rugosus. It 
