914 DR F. R. C. REED ON THE 



swollen near beak, with strong median sinus, having flat floor and steep sides, 

 in (leasing in width to margin and ending in rounded short obtuse tongue more or 

 less strongly bent up to meet fold in opposite valve ; beak rather swollen, rising- 

 above hinge-line, incurved ; hinge-area small, steeply inclined, triangular ; lateral 

 lobes of valve somewhat swollen ; teeth small, supported on thin divergent dental 

 plates ; muscle-scars very faint. Brachial valve swollen, slightly emarginate in 

 front, with abruptly elevated rounded median fold increasing in width to margin 

 and having steep sides and flattened top ; lateral lobes rounded, dependent ; beak 

 swollen, less high but more incurved than that of opposite valve ; interior of valve 

 with stout cardinal process (base only known) and pair of short rod-like crura ; two 

 pairs of faint subcircular large adductor scars, the posterior ones better marked and 

 separated by narrow sharp transverse curved ridges from anterior pair. Surface of 

 valves ribbed, having 6-7 low subequal or equal subangular or rounded closely placed 

 ribs both on the fold and in the sinus, and 8-13 rather larger simple similar ribs of 

 uniform size on each lateral lobe slightly curved back ; occasionally the ribs on fold 

 and in sinus increase in number by division. 

 Dimensions. — 



(1) (2) 



Length . . . . . .18 13 mm. 



Width 21 17 mm. 



Horizons. — (l) Stinchar Limestone Group ; (2) Balclatchie Group. 



Localities. — (l) Craighead ; (2) Ardmillan, Dow Hill, Balclatchie. 



Remarks. — This shell is seen by its internal and external characters to belong to 

 the genus Cliftonia, Foerste, and it is allied to Triplecia plicata, Wiman,* from the 

 Leptsena Limestone, and T. Ulrichi, Winch, and Schuch.,f from the Lorraine Group. 

 It is not always easy to distinguish specimens of it from Orthis (Platystrophia) 

 biforata, but the ribs in the sinus are always more numerous and smaller than in 

 that species. The Balclatchie examples usually have fewer ribs on the fold and 

 on the lateral lobes than the Craighead specimens, and the outermost ribs on the 

 fold are sometimes smaller than the others. We name it in honour of Mr Thomas 

 Anderson, who was a well-known collector of fossils in Girvan. 



Cliftonia spiriferoides (M'Coy). 



1851. Stropltumena spiriferoides, M'Coy, Ann. Mag. Nat. Hist., p. 402. 



1870. Orthis spiriferoides (M'Coy), Davidson, Mon. Brit. Foss. Brack., vol. iii, pt. vii, p. 275, pi. xxxvii, 



figs. 3-7. 

 1883. Triplecia spiriferoides (M'Coy), Davidson (pars), ibid., p. 224. 

 Non 1883. Triplecia spiriferoides (M'Coy), Davidson, ibid., vol. v, Silur. Suppl., p. 146, pi. viii, fig. 30. 



This is a rare species in the Girvan area, but two well-preserved internal casts 

 and two external impressions occur in Mrs Gray's collection from the Starfish Bed. 

 Davidson records it from Thraive in his list of Girvan brachiopods (op. cit., p. 224). 



* Wiman, Arkivf. Zool. Stockholm, Bd. iii, No. 24, 1907, p. 12, t. ii, figs. 13-17. 



t Winchell and Schuchert, Palxont. Minnesota, iii, 1893, p. 409, text-figs. 34a-e. 



