292 
DEVONIAN FAUNA. 
has given the name PL suhcancellata, leaving Phillips' name for the present form 
unchanged. As I have no other evidence as to the priority, I have followed 
d'Orbigny in this point. 
Affinities. — The English specimens of PI. Orbigniana^ d'Archiac and de Verneuil, 
seem to have less quadrate whorls, and the sinus-band is situated very much 
farther from the suture, near the base instead of in the centre of the whorls. 
These points are less distinctly shown in the Sandberger's figures of the German 
shell. Its ridges also appear to be wider apart, and the transverse striae finer 
and more oblique. 
PL suhclatlirata, Sandberger, is a much more angulated shell. 
PL subimbricata, Whidborne, is more conical, and has very much more 
numerous and finer strige and a rather higher sinus-band. 
» 11. Plbueotomaeia Chudlbighensis, Whidborne. PI. XXVIII, figs. 2, 3, Sa. 
c£. 1860. Pletjeotomabia Bodana, F. A. Bomer. Beitr., pt. 4, p. 163, pi. xxv, 
figs. 16 a, h. 
1889. — Chtjdleighensis, Whidborne, Geol. Mag., dec. 3, pt. 6, 
p. 30. 
Description. — Shell small, ovate, turbinate, few whorled. Spire conical, rather 
depressed, of four subangulated whorls. Suture deep, acute, facing upwards. 
Whorls regularly and moderately convex in general shape, covered with strong 
spiral ridges. Sinus-band on shoulder just above the widest part of whorl, rather 
elevated, bounded by two strong narrow ridges giving the angulated appearance 
to the whorl, and sometimes bisected by a fine median thread. Ornament 
consisting of two strong acute ridges below the suture, of which the first forms 
the steep side of the suture, and which are followed by two fine threads ; after 
which come the ridges or keels of the sinus-band, and then over the back and base 
of the whorl about twenty regular, smaller, spiral ridges or coarse threads, 
occasionally alternating, which diminish as they approach the umbilicus ; the 
whole series of spiral lines being crossed and knotted by fine and closer longitu- 
dinal threads, which sweep obliquely back from the suture, arch suddenly for- 
ward in the sinus-band, and then gradually curve over the back of the shell till 
on the lower part they again slope backwards, but begin to curve forwards again 
at the extreme inferior point. Umbilicus small, rounded. Columella twisted, 
curved, and rounded. Mouth sub-circular or sub-polygonal, posteriorly obtuse, 
knotched at the keel. Lips blunt. Shell-structure thick. 
Size. — One specimen is 14 mm. high and 16 mm. wide; another is 17 mm. 
