84. BRITISH SILURIAN BRACHIOPODA. 
Genus—SPiriFER, Sowerby, 1815. Sprririrnra, Phillips. 
SPIRIFERA PLICATELLA, Linn., sp. PI. IX, figs. 9—12. 
ANOMIA PLICATELLA, Linneus. Systema Nature, 12th ed., p. 1154, 1767. 
DELTHYRIS CYRTHNA, Dalman. Kongl. Vetenskaps Handlingar. for 1827, p. 120, tab. 
iii, *fig. 3 (Stockholm, 1828). 
— — Hisinger. Lethza Suecica, p. 73, pl. xxi, fig. 4, 1837. 
SPIRTFER INTERLINEATUS, J. de C. Sowerby. Silurian System, pl. xii, fig. 6, 1839. 
— — Dav. Bull. Soc. Géol. de France, 2nd ser., vol. v, p. 324, 
1848. 
— PLICATELLUS, var. INTERLINEATUS, Salter. Memoirs of the Geological Survey, 
vol. ii, p. 381, 1848. 
SPIRIFERA CYRTHENA, M‘Coy. British Pal. Foss., p. 193, 1852. 
ANOMIA PLICATELLA, Hanley. Ipsa Linnezei Conchylia, p. 127, 1855. 
SPIRIFER CYRTMNA, Schmidt. Silurische Formation von Ehstland; Archiv fiir die 
Naturkunde Liv.-Ehst-und Kurlands, vol. ii, p. 211, 1858. 
— PLICATELLUS, var. INTERLINEATUS, Salter. Siluria, pl. xxi, fig. 1, 
1859. 
SPIRIFERA PLICATELLA, var. INTERLINEATA, Lindstrom. Bidrag till kannedomen om 
Gotlands Brachiopoder (Proceedings of 
the Royal Acad. of Sciences of Stock- 
holm), p. 358, 1860. 
Spec. Char. Rhomboidal, longer than broad; valves gibbous, the ventral one being 
considerably arched ; beaks approximate; hinge-line shorter than the width of the shell, 
the cardinal or lateral angles beng rounded. Ventral valve most convex, with a deep 
longitudinal sinus extending from the extremity of the beak to the front; beak incurved, 
area triangular, fissure partly arched over by a convex pseudo-deltidium. Dorsal valve 
gibbous, with a more or less elevated mesial fold, flattened or depressed along the middle ; 
lateral portions of the valves more or less deeply divided into a greater or smaller number 
of large rounded ribs, while the entire surface of the shell is covered with numerous close, 
fine, subequal costze, and which are crossed by still finer concentric, thread-like, elevated 
lines. ‘Two specimens measured— 
Length 14, width 15, depth 12 lines. 
A Say i eliOurea ta melbc ae 5: 
Obs. The determination of this species and of some of its varieties or variations in 
shape has been attended with some difficulty. First of all, the name the shell should 
retain has led to some difference of opinion. Mr. Salter was the first to refer to the 
Linnean Cabinet for these Silurian Brachiopods, and there found specimens agreeing 
with the British fossil; and Mr. S. Hanley agrees with him: but the reference 
“ Anomia angulis lateralibus dilatatis dentibus alternis” im the ‘ Museum Tessinianum,’ 
