322 CARBONIFEROUS LAMELLIBRANCHIATA. 



which has the umbo of the left valve removed and the ossicle well exposed (fig. 5, 

 PI. XXXV). This specimen was obtained from the Middle White Limestone of 

 Craig-Fawr, North "Wales. 



Fig. 6, PI. XXXIV, is a specimen in my own collection, which shows the cast 

 of the interior muscle-scars and a slit which corresponds to the ossicle. The 

 strongly developed accessory muscle-scar is very well shown. 



Figs. 11, 11a, PI. XXXV, show portions of the exterior of the shell, with the 

 peculiar punctate markings arranged in radiating rows. I have not been able to 

 decide definitely whether these markings existed in the upper layer of the shell, 

 or were confined to the periostracum only. Unfortunately, specimens which 

 retain the shell are exceedingly rare. 



The vertical range of this species seems to have extended up into the Gaimister 

 series in Durham. De Verneuil {op. cit.) has figured a very fine cast, showing 

 the groove for the ossicle, from the Carboniferous Limestone of Stolobinskoi, 

 Russia ; and de Ryckholt a species from the Carboniferous shales of Tournai ; 

 but beyond these two records nothing is known of the distribution of this species 

 in the Carboniferous beds of Europe. De Koninck does not describe the species 

 in either of his great works. 



Tornquist has evidently made a mistake in referring his specimens to this 

 species ; his figures have nothing in common with Phillips's species. 



Edmondia expansa, sp. nov. Plate XXXIII, figs. 16, 16 a; Plate XXXIV, figs. 1, 



2, 4, 7. 



Specific Characters. — Shell large, transversely oblong-oval, inequilateral, com- 

 pressed. The anterior end is short, deep, with a rounded border, the lower part 

 being the arc of a much larger circle than the upper. The lower border is long, 

 very convex in front, then becomes almost straight, till it becomes convex again, 

 when it passes into the posterior border. The latter is extensive, almost semi- 

 circular. The hinge-line is much shorter than the antero-posterior diameter, and 

 is curved in front, but is straight posterior to the umbo. The umbones are small, 

 elongate, pointed, incurved, hardly raised above the rest of the shell, and placed 

 in the anterior fourth of the valve. The valves are only slightly convex from 

 before backwards, but a little more so from above downwards, and somewhat 

 compressed along the dorsal slope. 



Interior. — No details beyond the fact that the shell possesses the characteristic 

 ossicle have been yet observed. The interior of the shell had strongly marked 

 concentric rugae and folds. 



Exterior. — The surface is ornamented with regular close-set concentric folds 



