534 DR WHEELTON HIND ON 



and unfortunately it is not well preserved in the umbonal region ; but it shows the 

 peculiar dorsal slope of the genus, and has the characteristic ornament. 



Salter's type was obtained from Deerhope, a locality assigned to Upper Ludlow beds. 



Genus Cypricardinia, Hall, 1859. 



Cypricardinia, Hall, 1859, Geol. Surv. Neiv York, Pal., iii. p. 266. 



,, ,, 1885, ibid., vol. v., pt. i., Lamell., ii., pt. ii., p. xlvii. 



,, Miller, 1889, N. Amer. Geol. and Pal, p. 475. 



Generic Characters. — Shell inequi valve. The right valve more convex, very 

 inequilateral ; subrhomboid, obovate or sometimes trapezoidal, wider posteriorly. 

 Anterior end short, declining from the beaks and rounded below. Posterior end wider 

 and obliquely truncate. Beaks subanterior, incurved and adpressed. Umbo of the 

 right valve often prominent. Cardinal line straight or arcuate, rising from the beaks. 

 Umbonal slope prominent, often obtusely angular. 



Surface marked by strong concentric lamellose undulations with intermediate fine 

 striae of growth, and in some species by radiating striae, which are interrupted at the 

 outer margin of the lamellse. The valves are crossed obliquely by a shallow byssal 

 sinus. 



Hinge line marked by a long fold or lateral tooth in one valve. Cardinal teeth not 

 determined. Ligament external, strong, leaving in the cast a deep elongate groove. 

 Anterior muscular impression small, situated just within the anterior margin of the 

 shell. Posterior muscular impressions large and strong, situated on the cardinal and 

 umbonal slope, a little behind the middle of the length. Pallial lines parallel with the 

 margin of the shell. 



Observations. — I have quoted Hall's 1885 description at length (op. supra cit.), 

 as I had only a single fragment to study. This fragment evidently, from its sculpture, 

 agrees more closely with Cypricardinia than with any other genus. 



Cypricardinia lineata, sp. nov. (PI. V., fig. 20.) 



Specific Characters. — Shell small, transversely subrhomboidal, almost equilateral. 

 Anterior end rounded, its upper angle produced. Hinge line and superior borders 

 subparallel ; posterior border obliquely truncate. The umbones are moderately gibbose, 

 subcentral, dorsal slope compressed. 



Interior. — Not known. 



Exterior. — The surface is ornamented with distinct parallel, concentric, raised, 

 equidistant ridges. 



Dimensions. — Fig. 20, PI. V., a left valve measures : antero-posteriorly, 10 mm. ; 

 dorso-ventrally, 5 mm. 



Locality. — Ardmillan, Llandeilo series. 



Observations. — Unfortunately, the material on which I have been obliged to found 



