320 BRITISH SILURIAN BRACHIOPODA. 



and is distinguished from it moreover by the shape of its muscular impressions. Some 

 examples are extremely elongated or spindle-shaped {Lept. Duvalii, Dav.) ; while others 

 are almost as long as broad. Strophomena Fletcheri, which was confounded with it by 

 Mr. Salter, is a completely distinct species. At p. 267, vol. iii, of the ' Memoirs of the 

 Geol. Survey/ Mr. Salter proposes to designate a variety of L. transversalis by the name 

 of mididata (which would include Lept. quinquecostata of M'Coy, in part) ; but as he did 

 not figure or describe his variety, nor inform us what part of L. quinquecostata is to be 

 included in it, I cannot possibly adopt the designation. It is said to occur at Alt-yr- 

 Anker, Meifod, and Llanfyllin, in the Caradoc. 



Position and Locality. Leptcena transversalis occurs in the Caradoc, Llandovery, and 

 Wenlock formations. 



In the Caradoc at Glyn Ceriog, Denbighshire ; at Bala, &c., Merionethshire ; at 

 Helm Gill, Dent, in Coniston Limestone, &c. 



In Lower Llandovery at Mathyrafal ; Pen-y-Craig, Llangynyw ; at Ridge, behind 

 Penroch, and Cefnrhyddan, Llandovery ; at a quarter of a mile south-east of Cwm- 

 rhyddan ; Castellmadoc, south of Cilgwyn Road, &c. Also in Upper Llandovery at 

 Robeston Wathen, Pembrokeshire. 



In the Woolhope beds south of Woolhope. 



In the Wenlock Limestone and Shale at Dudley, Benthall Edge, Buildwas, near 

 Wenlock; Rushall Canal, near, Walsall; Sibdon, Shropshire, &c. 



In Scotland it occurs in Lower Silurian beds at Penwhapple Burn and Penkill, near 

 Girvan, in Ayrshire ; also in the Wenlock Shales of the Pentland Hills. 



In Ireland it is stated by M'Coy to be found in the Slates of Ardaun Cong, County 

 Galway ; but as Leptana sericea and some other allied forms have been so often con- 

 founded with Lept. transversalis, one must be careful in recording for it Lower Silurian 

 localities. It was, however, found in Upper Silurian at Perriters Cove. 



Abroad it is common in the Upper Silurian beds of Gothland ; and in Norway, 

 Esthonia, Bohemia, the United States, the Island of Anticosti {Flectamhonites area and 

 PI. tenera of Shaler), and in many other localities. 



r«nV2fy— YouNGiANA, Dav. PI. XLVII, figs. 19 and 20. 



This appears to be an ancient variety, or perhaps the original progenitor, of Leptana 

 transversalis. This shell is almost circular, or as wide as long, with a hinge-line slightly 

 shorter than the greatest width of the shell. Some specimens are even slightly longer 

 than wide. It measures ten lines in length, by about the same in width; and the ventral 

 valve is very convex or involute. In certain examples the concentric lines of growth 



