SANGUINOLITES STRIATUS. 401 



and finds tliem identical. This species is now referred to Sphetiotus by Hall, and 

 stated to come from beds of Devonian age. One can understand, knowing de 

 Koninck's views, why he referred shells from Vise and Tournai to difi'erent 

 species ; but on similar grounds there is much less reason for accepting as 

 identical the shells from Tournai and Burlington, U.S. 



There is no doubt, however, that Sphenotus rigidus, as figured by Hall, is 

 extremely like 8. striato-lamellosiis in its more regularly striate forms. 



Sanguinolites stbiatus, sjj. nov. Plate XLVI, figs. 1, 2; Plate L, fig. 22. 



? Sanguinolites plicatus, Kirhhy, 1S80. Quart. Journ. Geol. Soc, vol. xxxvi, 



p. 589. 



Specific Characters. — Shell of moderate size, transversely oblong, very inequi- 

 lateral, compressed, with a well-marked oblique ridge. The anterior end is short, 

 depressed, and narrow, projecting forwards in front of the umboues, and having a 

 rounded border. The inferior margin is transverse, and, though convex at both 

 ends, is almost straight for the greater part of its extent. The posterior border 

 is slightly expanded, obliquely truncate from above downwards and backwards, 

 and almost straight. It joins the lower border at a blunted right angle, but forms 

 a well-marked obtuse angle above with the hinge-line. The latter is straight, 

 extending backwards. The uuibones are smnll, elongate, incurved, and twisted 

 forwards, placed very close to the anterior end, and not much raised above the 

 posterior part of the shell. Passing obliquely downwards and backwards towards 

 the j)ostero-inferior angle is an angular fold, which marks off the dorsal slope 

 from the rest of the valve. The valve is only slightly convex, and has about its 

 centre an oblique compression, which becomes broader and shallower as it 

 approaches the lower margin. The dorsal slope is compressed and flattened. 



Interior. — The anterior adductor muscle-scar is large, rounded, marginal, with 

 a ridge on its posterior margin ; the posterior scar longer, very shallow, situated 

 on the dorsal slope immediately below the hinge-line, but remote from the 

 posterior margin. The pallial line is entire, often punctate. The hinge is 

 thickened and rolled behind, but in front is unknown. 



Exterior. — The surface is adorned with fine regular concentric lines and strity 

 of growth, which become almost obsolete on the dorsal slope. 



Dimensions. — PI. XLVI, fig. 2, from Skolie Burn (in the collection of the 

 Geological Survey of Scotland), measures — 



Antero-posteriorly . . .67 mm. 



Dorso-ventrally . . .27 mm. 



From side to side . . .10 mm. (estimated). 



52 



