. .SANGUINOLITES ANGUSTATUS. 367 



parallel with the inferior border. The iimbones are elongated, small, gibbose, 

 incurved and contiguous, very slightly elevated above the hinge-line, and placed 

 in the anterior fifth of the valve. Passing downwards from the umbo to the 

 postero-inferior angle is a rounded ridge, which separates the anterior convex 

 part of the valve from the rapidly compressed dorsal slope. In very large 

 examples this part of the shell is subdivided into two more or less equal parts 

 by a less apparent linear ridge, which terminates about the centre of the 

 posterior border. Lunule and escutcheon well developed. The latter is 

 elongate and narrow. 



Interior. — The adductor scars are almost obsolete. The anterior portion of 

 the hinge-plate has not been seen ; posteriorly it has a rolled and thickened edge. 

 Pallial line entire. The oblique ridge is not nearly so well marked in casts as it is 

 in testiferous examples. 



Exterior. — The surface is ornamented with equidistant, regular, concentric, 

 elevated, rounded ridges, which are crowded together in front, but become some- 

 what separated by deep narrow grooves as they pass backwards, where they all 

 appear to terminate abruptly at the oblique line which passes from the umbones- 

 to the postero-inferior angle. These ridges, however, much flattened and 

 compressed, bend suddenly upwards and pass to the superior border, becoming 

 bent again in a forward direction at the oblique line which bisects the dorsal 

 slope. The ridges and grooves are themselves smooth. Shell thin. 



Dimensions. — Fig. 3, PL XL, from Poolvash, Isle of Man, measures — 

 Antero-posteriorly . . . .55 mm. 



Dorso-ventrally . . . .22 mm. 



From side to side . . . .16 mm. 



Localities. — England : the Carboniferous Limestone of Bolland, Yorkshire ; 

 Narrowdale, Staffordshire; Castleton and Thorpe Cloud, Derbyshire. Poolvash, 

 Isle of Man. Scotland : Lower Limestone series of Kerrsland Glen, Beith, 

 Ayrshire ; Easter Bucklyvie, Donibristle, Fife. Ireland : the Carboniferous 

 Limestone of Bruckless and Anakish Quarry, Coi-k. 



Observations. — This species was described by Phillips under the generic name 

 Sanguinolaria, and the species was adopted by M'Coy and made the type of 

 8anguinolites. Fortunately the type specimen has been preserved and is now in 

 the Gilbertson Collection of the British Museum (Natural History), and I am 

 able to refigure the specimen, PI. XL, fig. 1, by the kind permission of the 

 authorities. It is a fairly full-grown shell, and is stated to have come from 

 Bolland. 



A comparison of the type of M'Coy's 8. discors, fig. 2, PI. XL, which is 

 preserved in the G-riffith Collection of the Science and Art Museum, Dublin, 

 demonstrates that it is the young of S. angustatus, and therefore must be 



