136 DEVONIAN FAUNA. 



Size. — Height 11 mm., length 12 mm. 



Localities. — A small distorted right valve, from the lane between Wrafton and 

 Heanton, is in my Collection. A slab containing a similar right valve, together 

 with a left valve which may belong to the same species, is in the Porter Collection 

 from the neighbourhood of Pilton. 



Remarks. — Whether these two valves, which are differently ornamented, 

 belong to the same species remains to be proved. It appears safest so to regard 

 them, as they occur together on one block of stone, and each seems quite 

 different from any other Pilton species. 



The first figured specimen of the right valve is worn and defective ; a specimen 

 found since shows that the rays bear strong transverse tubercles on their summits. 

 What indications there are of transverse lines tend to confirm the identity of the 

 two valves. 



Affinities. — The left valve closely approximates Pterinopecten exfoliatus, Hall, 1 

 but appears to have a sharper and less oblique umbo ; while the radiations on our 

 right valve are not obsolescent. It is possible that better specimens might prove 

 it identical with one, if not both of our valves. 



Pt. undosus, Hall, 2 though different in ornament, has the front wing as deeply 

 defined and notched as that of the present species. 



Some species of Aviculopecten given by Hall do not differ very greatly ; in fact, 

 Pterinopecten and Aviculopecten so run into each other that it seems difficult to 

 find a line of demarcation. 



Pecten sequalis, M'Coy, 3 has fewer rays and a smaller and more definite hind 

 wing than is seen in our left valve. 



Aviculopecten Neptuni, Goldfuss,* sp., as given by Freeh/ approaches our left 

 valve in shape and general appearance, though not in size, ornament, or convexity ; 

 but it differs much from our right valves. 



4. Pterinopecten Austeni, F. A. Bomer, sp. Plate XV, figs. 10, 10 a, 11. 



1855. Aticula Austeni, F. A. Bomer. Beitr. Harzgeb., pt. 3, p. 37, pi. vii, 



fig. 16. 



Description. — Left valve rather small, wider than long, flatfish, slightly 

 oblique, subcircular. Umbo rounded, prominent, proximate, situated somewhat 



1 1884, Hall, ' Pal. N. T.,' vol. v, pt. 1, p. 61, pi. i, figs. 16, 17 ; and pi. lxxxiii, figs. 6, 7. 



2 Ibid., p. 72, pi. ii, figs. 10—19 ; and pi. lxxxii, fig. 7. 



3 1844, M'Coy, ' Syn. Carb. Foss. Ireland,' p. 89, pi. xv, fig. 13. 



i 1834-40, Goldfuss, ' Petref. Germ.,' vol. ii, p. 125, pi. cxvi, figs. 4«, b. 



5 1891, Frecb, < Abhandl. Geol. Specialk. Preuss.,' vol. ix, pt. 3, p. 18, pi. ii, figs. 1, 2. 



