RHYNCHONELLlDiE. 



161 



Pentamerus, and in which, I trust, the species under description will find a permanent 

 home. 



As already stated, Stricklandinia lirata varies greatly in its external shape, and this 

 will be best understood by a glance at PI. XX, wherein are represented some of the best 

 examples of this species I have been able to assemble from our British collections. The 

 size and regularity of the ribs are especially variable in different specimens, as well as the 

 length of the hinge-line. In Sweden the shell has been found in a perfect condition; but 

 in our British rocks we rarely find any portion of the shell itself preserved. Very good casts, 

 however, especially of the interior, are common, and in those belonging to the dorsal valve 

 (as may be seen in PI. XX, fig. 11) there exist two elongated pits (the casts of the crural 

 processes), whose length can be easily ascertained by the introduction of a pin or needle. 



Position and Locality. Stricklandinia lirata appears to range from the Lower 

 Llandovery to the lowest portion of the Wenlock series. It occiu-s in the May Hill 

 Sandstone of Howler's Heath, south end of the Malverns; also near (north-east of) 

 Chirbury ; at Nash Scar, Presteign ; Huntley Hill ; Llangadock, South Wales, &c. 

 Sir R. I. Murchison found it in the Woolhope beds of Woolhope ; and Mr. Salter 

 found it in the lowest Wenlock beds of Marloes Bay and Marloes Mill (Survey Catalogues). 



In Ireland it occurs in Lower Llandovery grey slate at Cappacorcogue, Cong, Galway ; 

 and in higher beds at Uggool, Ballaghaderreen, Mayo. 



Abroad, Dr. Lindstrom found finely preserved examples in the " Wisby group " of 

 Gothland. In North America the Geological Sun^ey of Canada obtained St. lirata at 

 East Point, South-West Point, Heath Point, and the Jumpers, in the Island of Anticosti. 



Stricklandinia lens, /. de C. Sow. (sp.). PI. XIX, figs. 13 — 23. 



Ateypa lens, J. de C, Sowerby. Sil. Syst., pi. xxi, fig- 3, 1839. 



Spibifer ? L.5:vis, Id. lb., pi. xxi, fig. 21. (Not Penfamenw /«t"i>, J. Sow., 



Min. Con., pi. xxviii, fig. 2; nor Pent. Icevis, J. de C. Sow., Sil. 



Syst., xix, fig. 9 ; P. IcbvU being the young of Pent, oblongus.) 

 Pentamerus lens, M'Coy. Brit. Pal. Foss., p. 209, 1852. 



— MICROCAMERUS, M'Coy. Annals and Mag. of Nat. Hist., 2nd ser., vol. 



viii, p. 290 ; and Brit. Pal. Foss., p. 210, 1859. 



— LENS, Morris. Cat. of Brit. Foss., p. 142, 1854. 



— — Salter. Siluria, 2nd ed., p. 100, Foss. 14, fig. 1, and pi. viii, figs. 



9, 10, 1859. 



Steicklandia — Id. Billings, Canadian Journal, p. 51, fig. 88, 1861. 

 Stricklandinia — Billings. Cat. Sil. Anticosti, Geol. Survey of Canada, p. 45, 1866. 

 Pentamerus — Salter. Mem. Geol. Survey, vol. iii, pp. 276 and 360, 1866. 



Spec. Char. Longitudinally oval, sides and front rounded, greatest width nearer the 

 beak. Valves moderately and almost equally convex or deep. Hinge-line nearly 

 straight, and less than the width of the shell. In tbe dorsal valve there is a rounded 

 mesial fold, of moderate elevation, which in front forms a convex lobe. In this valve 



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