KONGL. SV. VET. AKADEMIENS IIANDL. BAND. 19. N:0 6. 113 



Divisio V. INCIS-iE. 



25. Pleurotomaria labrosa J. ITali,. 



PI. IX figs, .-jn— .38. 



Pleitrot. lahrosa 1859. .T. Hall Pal. N. York vol. Ill, 339, pi. G6 f. 1—5, pi. G7 f. 6. 



Fleurot. bnlteata 1807. Lindstkom (not Phillips) Nomina foss. Gotl., 23. 



Fhurot. Inhrosn var. orcidev.x 18G8. J. H.VLi. 20:111 Rep. N. York St. Cab. l:st Ed. 'M3. 



Pleurot. occidens 18U8. Hall 2n:tli lUp. l:st Ed. .364, pi. If) (G) fi<f. 11 — 12. 



18G8. Id. 20:th Rip. Revised Ed., 392, pi. XV f. 11—12, pi. XXV f. 9—1(1. 



1875. Hall & WiiiTriELD Gool. Survey of Ohio, vol. II, 142, pi. 8 f. 2. 



1877. Oeiilert Bull. Soc. Geol., 585, pi. IX f. G, G a. 



1877. Miller American Fossils, 160. 



Shell turbinated, with a short spire and the body whorl enlarged many times 

 the size of the other whorls. Whorls five, almost flat or horizontal beneath the large 

 and prominent slit band, above it convex and ventricose. This band is situated beneath 

 the median line of the whorls, it is oblique with the surface directed downwards; the 

 thin and sharp edges (fig. 35) transform it into a deep groove, somewhat wavy in its 

 cour.se (tig. 33). The crescents (fig. 34) are thin, deeply incised lamellse, concentrically 

 striated, obliquel}' hiding behind each other. The inferior, flat side of the whorls is 

 transversally striated by crowded lines of growth, which are crossed by a several ele- 

 vated, longitudinal stria? in some specimens, while they are completely wanting in 

 others. The superior moiety of the whorls is firnamented by a number of spiral ribs, 

 which together with the longitudinal lines form a regular, cancellated trellis work. 

 There are also finer transverse stria^. The slit in the aperture continues open for a 

 long distance. The aperture is rather rhomboidal and angular in the four corners, 

 below, above and at the sides, in the lowest corner acuminate. The exterior lip is 

 thin and sharp, the interior or coluraellar border thick, smooth and callous, folded 

 back tightly against the body whorl, so that no umbilicus is visible. Height 48 

 niillini., breadth 45 mill., longitudinal diameter of the aperture 35 mill., transver.se 

 diam. 30 mill. 



It occurs in the soft shale at Wisby, at Westergarn, where the most numerous 

 specimens have been found, Stora Carlsu, Ejmunds, in the canal between Atlingbo 

 church and Hogriin, Klints in Boge and Lansa in Faro. It does not occur in the lime- 

 stone beds above the shale. 



This species is interesting in consequence of its being one of the few which 

 continue in the Devonian formation. It was first described by Hall from that forma- 

 tion and Oehlert later also found it in the oldest Devonian strata of the north of 

 France. Its geographical range is also great, as it has been found in England, besides 

 in N. America and France. In England it has been found in the Wenlock Strata at 

 Walsall according to a specimen in the Museum of Practical Geology in London, of 



K. .Sv Vrt. Akn.l HnoiU. li.l. l:i. N:o i;. 15 



