STKEBLOPTERIA CONCENTRICA. 127 



Streblopteria Buchiana, de Koninck, 1885. Ann. Mus. Roy. d'Hist. Nat. Im'Il,'., 



torn, xi, p. 208, pi. xxx, fig. 31 ; pi. 

 xxxix, fig. 9. 



Pai^eolima l^evis, Hind, 1903. Brit. Carb. Lanicll , vol. ii, p. 40, pi. xix, figs. 



13-16. 



Observations. — I unfortunately overlooked de Koninck's species when I described 

 Palseolima Ixvis as new. Since the publication of vol. ii, pt. 2, 1 have compared a 

 specimen from Vise with the Irish specimens, and am satisfied of their identity with 

 de Koninck's species. I think, however, that the characters of the shell warrant 

 its inclusion in Palseolima rather than in Streblopteria. 



Streblopteria concentrica, sp. nov. Plate XXV, figs. 1, 1 a. 



Specific Characters. — Shell of medium size, suborbicular, moderately convex. 

 The margin is almost circular, extending in an unbroken curve from the anterior 

 ear and including the lower two-thirds of the posterior border, where it gradually 

 curves outwards and terminates in a well-marked postero-superior angle. The 

 hinge-line is straight, and prolonged slightly posteriorly. The umbones are small, 

 sub-central. The anterior ear is small and triangular. No posterior ear, but a 

 compressed and expanded postero-superior angle. 



Exterior. — The surface is adorned with distinct, distant, subimbricating, con- 

 centric lines, which are parallel to the margin and pass over the compressed dorsal 

 slope to the hinge-line. 



Dimensions. — PI. XXV, fig. 1, measures — 



Antero-posteriorly . . . . 3G mm. 



Dorso-ventrally . . . .37 mm. 



Locality. — Scotland : Lower Limestone Series of Howrat. 



Observations. — Mr. Smith has a single specimen in his collection, probably a 

 right valve, from Howrat. It is not quite perfect at the umbo, and the whole of 

 the anterior ear is not present. I am in doubt as to which valve it is, because if it 

 be the right valve there is no byssal notch. If the convexity of the valve has not 

 been altered by crushing it is apparently a right valve, and the concentric mark- 

 ings favour this vieAv. The character of the posterior part of the hinge-line and 

 absence of posterior ear denote an affinity to Streblopteria, ^M'Coy '. I know of no 

 other Carboniferous shell with such well-marked and regular concentric markings. 



