306 BRITISH SILURIAN BRACHIOPODA. 



or to King's sub-genus Streptorhynchus. Several Palaeontologists, such as Fischer de 

 Waldheim (in 1809), and J. de C. Sowerby (in 1839), have referred specimens to Linne's 

 species which evidently do not belong to it ; and Mr. Sharpe long ago pointed out that 

 the shell in pi. xx, fig. 4, of the ' Silurian System/ erroneously referred to Strophomena 

 pecte7i, in reality belongs to Sir. expansa, a perfectly distinct species. I fear, likewise, 

 that Baron von Buch has confounded the Carboniferous Streptorhi/nchus arachnoideus with 

 the Linnean form. I have also determined beyond doubt that the Orthis minuta of 

 Haswell is only a very young shell of the species under description. Good describable 

 interiors of Slrophomena pecien have not yet been discovered. It is evident that the 

 muscles left but feeble impressions upon the inner surface of the shell. Orthis semicircu- 

 laris, Sow., is a young shell of the species under description. 



Position and Locality. In ' Siluria' Strophomena pecten is stated to range through- 

 out the Caradoc or Bala, Llandovery, and Wenlock formations. In the Caradoc it is said 

 to occur at Clyn Ceiriog ; Llangollen, Denbighshire ; and Ravenstone Dale. Also in the 

 dark limestone of Coniston, Lancashire (Sharpe), &c. In the Llandovery, at Hope Quarry, 

 Minsterley ; Capel Cerrig ; Huntley Hill ; May Hill, &c. At Littlehope in the Woolhope 

 Limestone. In the Wenlock, at Dudley, the Bell, near Walsall ; Benthall Edge, and at 

 Shucknall Hill, Woolhope, in the Aymestry Limestone, &c. &c. 



In Scotland it is very abundant in the Wenlock Shales of the Pentland Hills. 



In Ireland it occurs at Eerriters Cove and in other localities. 



Abroad it has been found in the islands of Gothland and Oesel ; Ostrogothia ; Klinle- 

 berg, Norway ; the Ural ; Tennessee ; New York, &c. 



Strophomena Orbignyi, Dav. (sp.). PI. XLII, figs, 12 — 14. 



Orthis Orbignyi, Dav. Bull. Soc. Geol. France, ser. 2ncl, vol. v, p. 320, pi. iii, fig. 



17, 1848. 

 Strophomena — Salter and Etheridge. Cat. Mus. Prac. Geol., p. 41, 1865. 



Spec. Char. Semicircular, wider than long, greatest breadth at the long straight hinge- 

 line; cardinal extremities pointed, and slightly extended into raucronate wings; sides 

 rounded ; front very slightly convex, sometimes almost straight. Ventral valve gently 

 convex ; area triangular, narrow ; fissure arched over by a pseudo-deltidium ; beak small, 

 not projecting. Dorsal valve very slightly concave. Surface of valves marked by 

 numerous strongish radii, with wide interspaces, with which are interpolated, at various 

 distances from the beaks, one or two smaller striae. The valves are likewise crossed by a 

 few concentric lines of growth. In the interior of the ventral valve the saucer-shaped 



