ORTHID. 247 
OrtuIs SoweErsytana, sp. nov. Pl. XXXV, figs. 27—31. 
ORTHIS CALLIGRAMMA, var. WALSALLIENSIS, Salter (not O. Walsalliensis, Dav.). 
Mem. Geol. Survey, vol. ii, p. 337, 
pl. xxii, figs. 6, 7. 
Spec. Char. Semicircular, longer than wide; hinge-line straight, slightly exceeding 
the width of shell ; cardinal extremities rounded ; dorsal valve evenly convex, but flattened 
at the ears. Surface of valve marked with upwards of fifty small radiating ribs, the 
larger number of which extend from the beak to the front, with a wide interspace 
between each two, in the centre of which is another smaller and shorter rib, the whole 
being crossed by fine concentric lines of growth. 
Length 9, width 13 lines. 
Obs. Of this species (?) I am acquainted with the exterior and interior of the dorsal 
valve only, and consequently can offer but a very incomplete description of its form and 
character. Mr. Salter described it (with a mark of interrogation) as O. calligramma, var. 
Walsalliensis (?), Dav., but I am quite certain that it is neither the one nor the other ;_by its 
shape and interpolated ribs it is at once removed from O. calligramma, and it has not the 
shape of O. Walsalliensis, which last is no more than a variety of O. rustica, Sow., as has 
been already explained. I also found, after a careful examination of the original specimen, 
that the ribs had not been quite correctly expressed in pl. xxi, fig. 6 @, of the 2rd vol. 
of the ‘Memoirs of the Geological Survey.’ Mr. Salter, however, states in his descrip- 
tion—‘“ This might be described as an extreme form of var. plicata, for its shape agrees 
well. But there are the following differences, which bring it nearer to the var. Wai- 
salliensis of the Upper Silurian (ours is a Lower Llandovery variety). The dorsal valve 
is more convex than in O. plicata, and the ribs, instead of being numerous and slightly 
interlined, divide into bundles of twos and threes from very near their origin, and again, 
sometimes branching at half-way down, form fascicles of four or five ribs. There is an 
approach, in the very numerous ribs, to the O. rustica, Sow., which I regard also as a 
variety. ‘That shell and O. rigida are, however, square and depressed, the latter furrowed 
down the middle. The shell here figured is in any case an extreme form, and yet the 
general aspect of the ribs, their rod-like form, cross stri, and regular intervals, above all 
the form and size of the interior tooth (cardinal process) of the upper (dorsal) valve, 
decide me in referring all these varieties to a single species.” I have already explained 
why I must dissent from this view. 
Position and Locality. Lower Llandovery, Gas-works, Haverfordwest ; Caradoc of 
Cefn Llwydlo, Brecknockshire (Salter). 
