STROPHOMEXID.E. 329 



a minute circular foramen close to its extremity. Dorsal valve slightly concave, following 

 the curves of the opposite valve ; hinge-area linear. Surface almost smooth, shining, 

 obscurelv marked with a few radiating striae and concentric lines of growth. Interior 

 details imperfectly known. In the interior of the dorsal valve the deviating brachial (?) 

 laminge are small ; the muscular scars are didded along the middle by a narrow rounded 

 ridge, which extends to about half the length of the valve. 



Length 4, width 7, depth ^ a line ; but the shell is usually found with smaller 

 dimensions. 

 Obs. In 1S39 Mr. J. de C. Sowerby described, under the designation of Leptcena 

 lavigata (' Sil. Syst.,' pi. xiii, fig. 3), one valve of a small Leptana " with projecting 

 angular ears at the extremities of the hinge-line ; surface shining, obscurely radiated 

 with minute concentric waves and a few radiating lines : Wenlock Shale, Burrington, 

 near Ludlow." Again, at p. 618, pi. viii, of the same work, he describes, under the name 

 of Lejjtcena lepisma, Dalm. (?), another small, semicircular, smooth species, with hinge- 

 line equal to or rather less than the width of the shell. In 1S48 Messrs. Philhps 

 and Salter seem to have erroneously described and figured the first-named species under 

 the designation of L. lepisma ; and this mistake is noticed by Prof. M'Coy in the 

 following manner : — " The figures given in the ' Memoirs of the Geol. Survev,' as above 

 quoted, under the name of LejjtcBua lepisma (Dal.), var. minor, with reference to pi. viii, 

 fig. 7, of the 'Sil. Syst.,' certainly belongs to this species {Leptana laevigata), in which 

 the faint broad striae are rarely to be found ; and Mr. Salter mentions that he doubts 

 the distinction himself of the L. Icevigata. Further, I might mention that there seems 

 to be no such species as L. lepisma described in any work of Dalman ; and the specimen 

 so-called by Sowerby I find agrees with Dudley specimens, which I have certainly 

 determined to be the young of L. transversalis, on comparison with a number of 

 Gothland species." Now, I agree with the first portion of ^LCoy's observations, but 

 quite dissent from the supposition that the so-termed Lejjfana lepisma of the ' Silurian 

 System ' is a young example of L. transversalis ; it does not even belong to the same 

 genus, being, as will be seen further on, an almost entirely smooth species of Chonetes. 

 In some examples of Leptana Icsvigata tlie small circular foramen at the extremity of the 

 beak is distinctly seen (fig. 4) ; but I am not sure that it is a Leptcena, and no good 

 interiors have been hitherto discovered. The Lejjfana lavissima, M'Coy (' Sil. Foss. 

 Ireland,' p. 27, pi. iii, fig. 7), appears to me to be the same as the shell under 

 description. 



Position and Locality. Leptcena Icevigata has been found in the Wenlock Shales of 

 Burrington, Salop; in the Lower Ludlow of Clungunford, Shropshire; at Ledbury, &c. 

 It is said also to occur at Builth. Several other localities are quoted by M'Coy, but, as 

 there has been much confusion between the two forms above recorded, I mention 

 those only of which I feel certain. 



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