ALLORISMA ANSTICEI. 429 



Interior. — The anterior adductor scar is oval, shallow, and marginal; the 

 posterior scar is large and oval, and placed immediately within the postero- 

 superior angle. The pallial line is entire, probably sinuated. The hinge-plate 

 leaves in casts no indications of hinge-teeth. The inner surface of the valve is 

 covered with concentric grooves and sulci, crossed by numerous fine, almost 

 obsolete, radiating lines. 



Exterior. — The surface is ornamented with fine concentric strias of growth, 

 best seen in front and along the inferior margin ; but these become obsolete over 

 the umbones and dorsal slope. The dorsal slope is crossed by two radiating lines, 

 which pass from the umbo to the posterior border. The stri^ are often divided 

 into groups by obsolete concentric grooves. Over the anterior third of the valve 

 the surface is finely tuberculated ; the minute raised points are arranged in 

 radiating rows. Shell thin. 



Dimensions. — PL XLIX, fig. 3, a specimen in my collection, from the Pennystone 

 Ironstone of Ooalbrookdale (the bed where the type was obtained), measures — 

 Antero-posteriorly . . . .70 mm. 



Dorso-ventrally . . . .34 mm. 



From side to side . . . .30 mm. 



Localities. — England : the Pennystone Ironstone, Ooalbrookdale, Shropshire. 

 Scotland : the Lower Limestone series of Auchenmade, Ayrshire. Ireland : 

 Chicken Hill, Kilmallock, co. Limerick. 



Observations. — This species was originally described by J. de C. Sowerby as 

 Unio Ansticel, in the appendix to Prestwich's 'Memoir,' p. 5Ul, but his short 

 descriptive note is meagre and contradictory. The type specimen, PI. XLIX, 

 fig. 2, is preserved in the British Museum (Natural History), South Kensington. 

 I do not know of any other specimens from the locality of Ooalbrookdale, except 

 the one in my possession. Both are in the form of casts, and my specimen, 

 PI. XLIX, fig. 3, shows the details of the interior very well. 



I have little or no hesitation in referring the Sanguinolites contortus of M'Ooy 

 to Sowerby's species. M'Coy's description agrees in every detail with the 

 characters exhibited by the Ooalbrookdale specimens. He says, " This species is 

 wider than the Unio Ansticei, and more nearly resembles the common S. tunnda ; " 

 but he does not enumerate any other distinctive characters between his specimen 

 and U. Ansticei. He gives two inches four lines as the width and length of 

 Sanguinolites contortvs ; Sowerby gives two and a half inches as the width 

 (leno-th) of Unio Ansticei; so that this statement is unwarranted. It must 

 be noted that Phillips gave Ooalbrookdale as one of the localities for his 

 Sanguinolites ? tumida, bub there is very great doubt indeed as to the real nature 

 of the shell he referred to under this title. Still there is no other species occurring 

 in Ooalbrookdale to which he could with any propriety have referred by this name. 



