PTERINOPECTEN PAPYRACEUS. 53 



Localities. — England: specially characteristic of the series of beds which 

 succeed the massif of Carboniferous Limestone, and found at many horizons as high 

 as the Middle Coal Measures. Derbyshire: Pendleside series of Mam Tor, river Noe, 

 near Castleton, and Railway Cutting, Tissington ; Coal Measures between top hard 

 coal and deep soft coal, Midland Railway Cutting, f- mile north of Pilsley Junction. 

 Staffordshire : Pendleside series of river Dane, in Swythamley Hall gardens, 

 Quarry near Mixon Hey, and the Coombes, near Leek; Coal Measures of Cheadle 

 Coalfield (above stinking coal) ; roof of thin coal about 42 yards above Tilborne 

 Coal ; Pottery Coalfield (above 7 ft. Banbury, and at Weston Coyney brick works, 

 and below the Twist Coal). Lancashire: Pendleside series of Pen die Hill, 

 Dinckley Hall, river Hodder ; above the Bullion Coal, Sholver, Colne, and uni- 

 versally; 150 yards over Great Mine, A shton-under-Lyne. Cheshire: Pendleside 

 series, E. of Bosley Minn. Shropshire : Pennystone Ironstone of Coalbrookdale. 

 Yorkshire : Pendleside series of the Vale of Todmorden, Pule Hill, Marsden ; 

 Flasby and Burnsall Fells; below the third grits at Eccup, and Wadsworth 

 Moor ; Coal Measures of Halifax (roof of the Hard bed), and universally at 

 that horizon. North Wales : Holywell Shales of Flintshire. Isle of Man : 

 Pusidcmomya-beds, Poolvash. Scotland : 2\ feet above the Calderwood Cement- 

 stone, Lower Limestone Group, East Kilbride; and ? above the Ell Coal, Wishaw. 

 Ireland : Pendleside series (Upper Limestone Shales) of co. Dublin ; Meath ; 

 Glenaster, Foynes Island, and Mount David, co. Limerick ; Roscliffe, co. Clare ; 

 Coal Measures of Firocla Colliery, Kilkenny ; Gannister series of Castlecomer. 



Observations. — This species is most important, as it is the characteristic Lamelli- 

 branch of a special fauna, and therefore of zonal value. Its zone is very thick, 

 measuring some 2000—4000 feet in some areas, but Pterinopecten ^qn/raceus 

 appears in the lower beds of this mass of rocks, and recurs at several horizons 

 throughout the series, which extends from the top of the massif of Carboniferous 

 Limestone to a layer high up in the Coal Measures. The species has been long 

 known, and it has been fully described by Sowerby, de Koninck, M'Coy, and 

 Etheridge. The slight differences which occur in the descriptions by these authors 

 arc doubtless all due to different degrees of preservation in the specimens studied. 

 To this matter Mr. It. Etheridge, jun., has called attention. Very frequently 

 /'. papyraceus is much compressed, but the true characters of the shell are best 

 observed in specimens preserved in nodules of black limestone. Well-preserved 

 specimens always show a well-marked anterior ear in both valves, but the posterior 

 ear is not marked off from the valve by a groove, and its margin extends slightly 

 beyond the rest of the valve, so that the posterior border is sinuous above. 



The marking of the shell is simple; a series of long, radiating, narrow ribs 

 which pass uninterruptedly from the umbo to the border of the valve, is separated 

 by smaller ribs which commence on the body of the valve between any two main 



