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DEVONIAN FAUNA. 



very long, nearly horizontal under the wing, and then obliquely convex. Inferior 

 margin rather narrow, roundly convex. Posterior margin nearly erect, sigmoid. 

 Contour of surface flatly convex in the centre, sinking steeply to the wings, 

 and sloping out to the lower margins. Surface covered by about eighty very 

 fine, narrow, distant, sharpish, rather irregularly alternating ribs, which are 

 rather coarser on the hind wing, and very indistinct on the front wing, but with 

 hardly any transverse markings except on the front wing, which bears about 

 seven rounded, parallel, regular undulations. Shell- structure thin. 



Size of left valve. — Length about 22 mm., breadth 18 mm., depth 5 mm. 



Locality, — Lummaton. There are three specimens in my Collection. 



Remarks. — Of these specimens the largest is the best, but does not show the 

 front wing ; the smallest is slightly narrower, and shows the front wing well ; the 

 third is a hardly recognisable fragment. 



It is not certain whether they may be identified with Avicula rudis, Phillips, 

 from Barnstaple, as his figure is extremely imperfect and his description vague. 

 As far as can be seen, the chief difference is that its transverse bulges are very 

 much more clearly visible, but this may be due to its being a crushed or older 

 shell. There does not seem, therefore, any reason for separating it. 



Pterinea Morleti, (Ehlert and Davoust, also appears to belong to the same 

 species, the figure of the French shell being exactly similar to my largest 

 specimen ; but some doubt must remain for the present, as neither of the two 

 shows the front wing. 



The species is characterised by its great breadth, slight obliquity, and fine 

 sharp ornament. The hinge-line meets the posterior margin at a sharp angle, 

 and the posterior wing is very broad. 



I have been unable to meet with Phillips's type, but there are two very 

 doubtful specimens in Mr. Townsend Hall's Collection from Sloly, which may 

 possibly belong to the same species. 



A. semiglobosa, F. A. Romer, may possibly be identical. Its figure, however, 

 seems to differ in having a smaller wing and a fuller anterior side. 



Affinities. — A. placida is longer and more oblique, and has coarser and closer 

 ribs and a larger wing. 



9. AfTiNOPTEBiA texturata, Phillips; sp. Plate IX, figs. 2, 2(1, 3, 3 £1, 5 — 7. 



1841. Avicula textttbata, Phillips. Pal. Foss., p. 51, pi. xxiii, figs. 87 a, b. 



1848. — — Bronn. Handbuch, pt. 3, p. 143. 



1849. — — d'Orbigny. Prodrome, vol. i, p. 84. 

 1854. — — Morris. Catal. Brit. Foss., p. 163. 



