196 BRITISH PALA®OZOIC FOSSILS. {Bracuiopopa. 
the Spirifer spurius of Barrande (Naturwissenschaftliche Abhandlungen Vol. 11. t. 18. f. 17) is the same as the 
Spirifer octoplicatus of Sowerby in the Silurian System, although I agree with them that that species is quite 
distinct from the true carboniferous . octoplicatus of the Mineral Conchology. The species figured in the 
Silurian System is distinguished from the S. spwrius (Bar. not Braun) by the much narrower mesial sulcus, and 
the want of ribs therein, unless they only appear in extreme age; in any case, M. d’Orbigny’s name is the 
proper one to retain for this species. 
Position and Locality—¥Extremely abundant in the hard, siliceous Upper Ludlow rock of Lamb-rigg 
Fell, Benson Knot, and N. end of Potter's Fell, Kendal, Westmoreland. 
SPIRIFERA (Cyriia@) TRAPEZOIDALIS (Dalm.) 
Ref. and Syn. = Cyrtia trapezxoidalis Dal. Act. Holm, 1827. t. 3. f. 2. 
Spirifer id. Davidson, Bull. Geol. Soc. de France, 2nd Series, Vol. V. t. 3. f. 43. 
Sp. Ch.—Entering valve nearly semicircular, twice as wide as long; cardinal angles rectangular, or 
obtusely rounded; mesial ridge large, strongly defined throughout, prominent, flattened above, forming 
a deep subquadrate lobe in the margin; sides gently convex; receiving valve pyramidal, w:th a very deep 
mesial suleus from the beak; hinge-line as wide as the shell; cardinal area triangular, or slightly incurved ; 
height varying from one-half to little more than one-third the width; surface uniformly radiated with very 
fine, close, thread-like strive, about eleven in one line at three lines from the beak, increasing in number 
towards the margin by intercalation. Average width (of small specimen) eight lines; proportional length of 
entering valve {5 5 height of cardinal area ;j, to 33. 
In casts the slits left by the dental lamellze are very strongly marked in the entering valve, and the 
centre of the ridge of the receiving valve shews traces of a fine mesial septum. 
Position and Locality—Common in the schists of Goldengrove, Llandeilo; schists of Coed Sion, Llan- 
gadoc, S. Wales ; Upper Ludlow rock of Woolhope. 
Genus. ATHYRIS (M‘Coy). 1844. 
Syn. = Spirigera (VOrb.) 1848. 
Gen. Char.—Nearly orbicular or ovate, both valves convex; no cardinal area, foramen, or hinge-line ; 
spiral appendages to beak of entering valve very large, nearly filling the shell; a strong mesial septum in 
rostral part of entering valve ; dental lamellze moderate; tissue of shell apparently fibrous. 
One specimen (of A. twmida) shews the pallial and ovarian impressions to be thick, numerous, and 
dichotomising frequently from the beak to the margin. 
ATHYRIS TUMIDA (Dal. Sp.) 
Ref. and Syn. = Atrypa tumida Dal. Acad. Holm. t. 5. f. 3.= A. tenuistriata Sow. Sil. Syst. t. 12. f. 3. 
Sp. Oh.—Rotundato-quadrate ; valves almost equally tumid; margins level in young specimens, raised 
in adults into a small obtuse square sinus, forming an obtuse ridge (sometimes divided by a faint mesial 
suleus) extending a small way from the margin on the small valve, but usually no corresponding depression 
in the receiving one; lateral margins nearly straight, front margin forming a rotundato-quadrate lobe 
towards the small valve: beaks very small, incurved, touching each other; apical angle about 115°; 
surface smooth, or rarely with a fine obtuse longitudinal lineation on the sides. Average width one inch 
eight lines; proportional length ;5,; length of entering valve =; depth of both valves *. 
When in good condition the surface is smooth, but when partially decorticated fine radiating strice 
appear, as I have noticed in nearly all the smooth species of Athyris and Martinia, On comparing the 
English and Gothland specimens I have no doubt that Mr Sowerby’s name should be considered a 
synonym of Dalman’s. 
Position and Locality.—Abundant in the Wenlock limestone and shale of Dudley, Staffordshire ; not 
uncommon in the Wenlock limestone of W oolhope. 
