LINGULID. 61 
OBoLELLA? PLUMBEA, Salter. PI. IV, figs. 20—27. 
LINGULA PLUMBEA, Salter, Siluria, 2nd ed., p. 50, Foss. 8, fig. 1, 1859. 
OzoLeLtA —  Id., Memoirs of the Geological Survey of Great Britain, vol. iu, 
p. 334, pl. xi B, fig. 10, 1865. 
Spee. Char. Broadly sub-triangular, as wide or wider than long, compressed laterally, 
and anteriorly broadly rounded, posteriorly or retrally acuminated; beak pointed ; valves 
almost equally deep and very slightly convex ; surface smooth, polished, and marked with 
many concentric lines of growth, and fine radiating strie. Two specimens measured— 
Length 8, width 8 lines. 
fuel TOY, 
Obs. Mr. Salter informs us that this is a remarkably broad species; but in general 
the width does not appear to have very much exceeded the length: we are also told that 
the muscular scars are remarkably strong and clearly defined, and are less divided or 
bilobed than even in O. pretiosa, Billings, in which species this undivided character is 
most conspicuous ; Mr. Salter is therefore of opinion that O. plumbea will probably in future 
form the type of a new genus, distinguished particularly by this union of the muscular 
scars ; and he has endeavoured to indicate this by the sectional name of Monodolina, the 
muscular scars being united closely along the central line. I have seen several fine 
specimens of the exterior of this shell; and I have figured the only two internal casts 
with which I am acquainted, showing muscular impressions ; these also were used by 
Mr. Salter in making his descriptions.’ It is possible that Odolella Salteri, Holl, may 
be nothing more than a synonym of the shell under description. 
Position and Locality. 'This species occurs abundantly in the Lower Llandeilo, west 
of the Stiper Stones, Shropshire, particularly at White Grit Mine, Shelve; it is also found 
at Ty Obry, two miles east of Portmadoc. In the Museum of the Geological Survey 
some specimens are labelled Hellpool, Wyeford, Builth. This is “ Upper Llandeilo ;” 
and it may be a mistake. 
P Opotetta Sarterr. PI. IV, figs. 28, 29. 
OpoLELLA Satrert, Holl. Quarterly Journal Geol. Soc., vol. xxi, pp. 101 and 102, 
fig. 9, 1864. 
This shell is described by Dr. Holl as “ compressed, sub-trigonal to nearly round, 
1 O. plumbea bears also some resemblance to Obolella chromatica, Billings, a species which in 
Canada occurs in limestone of the Potsdam group at the Anse an Loup, on the north shore of the Straits of 
Belle Isle. 
