396 CARBONIFEROUS LAMELLIBRANCHIATA. 



Dimensions. — PL XLIII, fig. 2, from the Carboniferous Limestone of Poolvash, 

 Isle of Man, measures — 



Antero-posteriorlj . . . .50 ram. 



Dorso-veutrally . . . .26 mm. 



Lateral elevation of valve . . .8 mm. 



Localities. — England : the Upper Carboniferous Limestone of Poolvash, Isle 

 of Man ; tlie Redesdale Ironstone, Redesdale and Bellingham ; and Lowick, 

 Northumberland . 



Observations. — De Rjckholt, when describing this shell, referred it finally to 

 Solenopsis, although he figured it originally under the name Pholadomya. 

 De Koninck retained the species under the genus Sanguinolites, to which it 

 undoubtedly belongs. There is a close resemblance between S. visetensis and 

 ;S'. tricostatus. The former is less transverse and comparatively deeper in tlje 

 dorso-ventral direction, and has a longer and narrow anterior end, and I also 

 agree with de Koninck that the diagonal fold is less pronounced. He thinks 

 that S. tricostatus has a reticulate surface, and that this character is absent in 

 8. visetensis ; but I have shown (see above) reasons for supposing that de Koninck 

 misunderstood the type of 8. tricostatus, and have called his reticulate shell 

 8. striafo-granulatus. There are undoubted traces of radiating rows present in 

 the shell from Lowick in the Woodwardian Museum, Cambridge, PI. XLIII, 

 fig. 4. This species seems to have had at times three distinct radiating lines on 

 the dorsal slope between the oblique fold and the edge of the escutcheon instead 

 of two, which de Koninck thought to be the normal number. I am inclined to 

 think that the number of these radiating lines is not of much specific value, 

 but may depend on crises in the growth of the shell, or extra longevity. 



The broad posterior end and the large rounded oblique gibbosity at once 

 serve to separate this shell from 8. tricostatus and S. striato-granulatiis. 



Sanguinolites obi.ongus, sp. nov. Plate XLIII, figs. 6, 7. 



Specific Characters. — Shell above the medium size, oblong, very inequilateral, 

 compressed, carinate, upper and lower borders parallel. The anterior end is 

 short, deep, and compressed ; its margin bluntly rounded, passing with a gradual 

 curve into the inferior border, which is almost straight for the greater part of its 

 extent, but curves slightly upwards behind to form a blunted almost right angle 

 with the posterior margin. The posterior border is obliquely truncate from above 

 downwards and backwards, almost straight, as long as the dorso-ventral diameter 

 of the shell about its centre, and forms a well-marked obtuse angle above with the 

 hinge-line. This is short and curved in front, but straight and produced posteriorly. 



