814 DR F. R. C. REED ON THE 



gently convex, beak marginal or submarginal, not much raised. Surface of both 

 valves marked with fine concentric striae and several (6-8) strong low radiating 

 wrinkles running from the apex to the middle of the anterior margin. Interior 

 of shell finely punctate. 



Dimensions. — Diameter, 3-7 mm. ; height, 1-2 '5 mm. 



Horizon. — Balclatchie Group. 



Localities. — Balclatchie, Dow Hill. 



Remarks. — It is probable that this shell is referable to the genus Acrothele, and 

 in its external ornamentation and shape it resembles A. subsidua (White) * and its 

 varieties. A. Mattheivi (Hartt) t and its varieties also seem to be allied. 



Acrothele (?) sp. a. 

 (Plate III, figs. 23, 24 ? 25 ?) 

 1883. Acrotreta Nicholsnni, Davidson (pars), Mon. Brit. Foss. Brack, vol. v, Silur. Suppl., pp. 213, 224. 



Shell corneous, subcircular to elliptical, wider than long. Brachial valve flattened, 

 slightly raised towards beak, with posterior edge nearly straight and a shallow broad 

 median depression on surface towards anterior margin ; beak small, submargina], 

 slightly raised, with traces of a pair of minute cardinal muscle-scars ; interior with 

 short median septum. Surface of shell marked with concentric lines very minutely 

 granulated. 



Dimensions. — Diameter about 5-6 mm. 



Horizon. — Balclatchie Group. 



Localities. — (l) Balclatchie, Ardmillan, Dow Hill. 



Remarks. — Some of the minute shells, labelled by Davidson Acrotreta Nicholsoni, 

 may be referable to Acrothele, but others (figs. 24, 25) may belong to Acrotreta. No 

 pedicle-valve which can be associated with them has so far been discovered. 



Acrothele (Redlichella ?) sp. b. 

 (Plate III, figs. 26, 27.) 



1883. Siphonotreta micula, Davidson (pars), Mon. Brit. Foss. Brach., vol. v, Silur. Suppl., p. 224. 

 Non 1851. Siphonotreta micula, M'Coy, Ann. Mag. Nat. Hist., ser. 2, vol. viii (1851), p. 389; Syn. 

 Brit. Pal. Foss. Woodiv. Mus., p. 188, pi. iH, fig. 3. 



There is a small horny brachiopod occurring at Balclatchie which much resembles 

 the small shells from the Llandeilo of Co. Down, referred by Davidson \ to Acrothele 

 granulata, Linnarsson,§ of the Middle Cambrian of Sweden, but it is probable that 

 the Llandeilo and Cambrian forms are nevertheless distinct, though Walcott || puts 



* Walcott, Uamb. Brach. (Mon. U.S. Geol. Surv., vol. li, 1912), p. 656, pi. lx, figs 1, 8, 9. 



t Ibid., p. 650, pi. lxi, figs. 1, 2, 3, 5. 



\ Davidson, op. cil, v, p. 214, pi. xvi, figs. 29, 30. 



§ Linnarsson, Bih. t. k. svensk. vet. Akad. HandL, Bd. iii, No. 12, 1876, p. 24, pi. iv, figs. 51a-c. 



|| Walcott, Camb. Brach. (Mon. U.S. Geol. Surv., vol. li, 1912), p. 663, pi. lvi, figs. 2, 2a-n. 



