132 DEVONIAN FAUNA. 



Localities. — A specimen from Barnstaple and two from south-west of Sloly in 

 the Woodwardian Museum, and two very indistinct shells from Sloly in the 

 Barnstaple Athenseum, appear to belong to this species. 



Remarks. — Under this heading Phillips has figured two very indistinct valves 

 from Pilton and Bradiford, viz. a left valve which closely resembles our specimens, 

 and a right valve showing the concentric lines described by him. 



Our fossils are all too indistinct to throw further light upon the species, or to 

 enable us to be certain whether the Lummaton form is identical. While most of the 

 specimens seem to have a rather large and rayed hind wing, in the specimen here 

 figured it seems short and smooth. Though this certainly throws a little doubt 

 on its identity, I am inclined to regard it as immaterial. The smoothness, at all 

 events, seems simply due to accidental obliteration of ornament. 



Affinities. — A. Jugleri, F. A. Romer, 1 approaches it most nearly, but is more 

 oblique, and, judging from the figures of it given by various authors, differs in 

 other particulars. 



7. Genus or Sub-genus— Pteeinopecten, Hall, 1883. 

 1. Pteeinopecten polyteichus, Phillips, sp. Plate XV, fig. 1. 



1841. Pecten polyteichus, Phillips. Pal. Foss., p. 46, pi. xxi, fig. 76. 



1S55. Avicula Ibeegensis, F. A. Bonier. Beitr. Harzgeb., pt. 3, p. 35, pi. vii, 



fig. 3. 

 1884. Pteeinea Ibeegensis, Clarke. Neues Jahrb. f. Min., Beil.-Band iii, 



p. 370. 

 1891. Avicula Ibeegensis, Freeh. Abhandl. G-eol. Specialk. Preuss., Band ix, 



pt. 3, p. 44, pi. iii, fig. 3. 



Description. — Left valve very large, nearly flat, rather oblique, higher than 

 long. Umbo probably very small, low, and situate at or about the anterior fourth 

 of the length of the value. Hinge-line straight, nearly equal to the length. 

 Margins unknown, but probably the inferior short, slightly oblique, and convex, 

 the postero-inferior slightly produced and broadly convex, and the posterior nearly 

 direct and gently sigmoid. Hind wing large, flat, broad, triangular, undefined, 

 and with a nearly perpendicular margin. Contour of back gently convex near 

 umbo, sloping out flatly to margins. Surface with about eight large, rounded, 

 distant, radiating ribs, rapidly decreasing in size laterally, between each of which 

 is an alternating series of seven very much smaller ribs, of which the fourth is the 



1 1843, F. A. Eomer, ' Verst. Harzgeb.,' p. 21, pi. vi, fig. 4. 



