DISCINID A. 67 
Cretaceous species, and consequently a question might arise as to which form may claim 
the name of /evigata. 
Discina oblongata, like all its congeners, varies considerably in shape, some specimens 
being more circular or more elongated than others ; and the free valve is also more elevated 
or conoidal in some specimens than in others; thus, in the Caradoc beds of Shropshire 
and Ayrshire, where the species occurs, some examples show much more elevation than 
what we perceive in Portlock’s typical specimens. 
Position and Locality. n Ireland D. oblongata and its varieties, levigata and sub- 
rotunda, were found in the coarse gritty Caradoc schists at Desertcreat; in sandy 
schists at Bardahessiagh, in the County Tyrone; and in slates at Tirnaskea, Co. Pomeroy. 
It has also been met with in the same beds at 'Tramore, County Waterford. 
In England Mr. Davies has found it in the Caradoc beds of South Shropshire (upper 
beds only—J. W.S8.). It occurs also at Llanfyllin, Montgomeryshire. 
In Scotland a variety is not rare in the Caradoc of the Girvan Valley in Ayrshire. 
P Discina? Vicaryi, Dav. Pl. VII, fig. 13. 
Spec. Char. Free or upper valve ovate, longer than wide, narrowed posteriorly, 
broadly rounded anteriorly, conoidal and moderately elevated ; vertex slightly incurved, so 
that its extremity is situated almost vertically above the middle of the posterior margin or 
a little incurved forward ; surface smooth (?); lower or attached valve not known. 
Length 8, width 7 lines. 
Obs. 'T'wo specimens in the state of casts of the upper or free valve of this Déscina (?) 
were found by Mr. Vicary in the red sandstone pebbles of Budleigh Salterton, in Devon- 
shire. Not possessing the lower or attached valve, I must leave the description and 
identification very incomplete and _ provisional. 
It is also uncertain whether this shell belongs to the Lower Silurian, since species 
of that period are mixed up in the locality with shells evidently of Devonian age. It 
is also at times difficult to distinguish certain species of Discina (?) from others of 
Metoptoma; for instance, JZ. estella of Billings bears some resemblance to our D. 
Vicaryi ; but this last is less conical than is the Canadian Gasteropod. [Mr. Salter 
would provisionally refer all the so-called Metoptome and Capuli from the Lowest Silurian 
or Potsdam groups to Discinide; and tells me that he has some such from his new 
‘Menevian’ group. 
Discrna striata, Sow. (sp.) Pl. VI, figs. 1—4. 
ORBICULA sTRIATA, Sow. Silurian System, tab. v, fig. 21, 1839; Siluria, pl. xx, 
fig. 3, 1859. 
Discina _ M‘Coy. British Pal. Fossils, p. 191, 1852. 
