124 DEVONIAN FAUNA. 



Hisinger, is congeneric, and is evidently closely allied. The specimens of it in the 

 Museum of the Geological Society show great variability, but appear distinguished 

 by their larger hind wing, which extends beyond the postero-inferior corner. As 

 Sowerby points out, 1 it is most improbable that the Silurian species can be the 

 same as Hisiuger's form, if it be Jurassic. 2 



3. Genus — Leiopteria, Hall, 1883. 

 1. Leiopteria Conradi, Hall? Plate XIV, fig. 7. 



?? 1881. Avicula (Pterinea?) seeviens, Barrande. Syst. Sil. Boheme, vol. vi, 



pi. ccxxiii, figs. 2, i_g, Et. E. 

 ? 1884. Leiopteria Coneadi, Rail. Pal. N. T., vol. v, pt. 1, p. 159, pi. xx, figs. 



1, 2, 4 : and pi. lxxxviii, figs. 1 — 4. 



Description. — Shell small, oblique, rather transverse. Hinge-line equal to 

 the length of the shell. Umbo small, acute, prominent, slightly elevated, 

 and situated close to the anterior end. Front wing very small, rounded. Hind 

 wing large, long, flat. Anterior and inferior margin long, oblique, gently curved. 

 Posterior margin long, deeply sigmoid. Contour very convex across the line from 

 the umbo to the postero-inferior region, in front of which it arches gently to the 

 margin, and behind which it sinks with a sigmoid curve to the hind wing. Surface 

 covered with rather numerous, concentric, irregular undulations, which appear to 

 have probably been covered by finer strias. 



Size. — Height about 14 mm., length about 16 mm., depth of valve about 5 mm. 



Localities. — One specimen is in the Woodwardian Museum from Barnstaple ; 

 and another in Mr. Hamling's Collection from near the Old Kiln at Croyde Bay. 



Remarks. — These specimens are very imperfect, the first being a cast and 

 defective in front, and the second being compressed in front, and affected by lines of 

 pressure which have obscured the ornament. It appears, however, that they 

 certainly belong to the genus Leiopteria; that, though differing considerably in 

 some particulars, they probably belong to the same species ; and that they are so 

 very similar to L. Conradi, Hall, as probably to be identical with it. If so, the 

 English shells probably belong to a dwarfed variety of that species. 



Affinities. — Leiopteria DeJcayi, Hall, 3 is less transverse, and has a much broader 

 wing. 



1 1839,'Sowerby, in Murcbison'a ' Sil. Syst.,' p. 609, pi. v, fig. 9. 



2 1826, Hiainger, ' Act. Holm.,' pi. vii, fig. 9 ; and ' Petr. Suec.,' p. 57, pi. xvii, fig. 12. 



3 1884, Hall, « Pal. N. T.,' vol. v, pt. 1, p. 164, pi. xx, figs. 16—18; and pi. lxxxviii, figs. 5—10. 



