806 DR F. R. C. REED ON THE 



showing through shell. Interior of pedicle* valve with double narrow low median ridge 

 from beak expanding suddenly at one-third the length of valve into low oval boss. 

 Dimensions. — 



0) (2) 



Length . . .107 11 '8 mm. 



Width . . . 7"0 8 - 2 mm. 



Horizon. — Drummuck Group (including Starfish Bed). 

 Locality. — Thraive Glen. 



Remarks. — This shell is much the shape of shells usually attributed to L. ovata, 

 M'Coy,* but the ornamentation is different. The poor interior of a brachial valve 

 from Drummuck, figured by Davidson (op. cit.) as L. ovata in his Supplement, may 

 belong to this species. 



Lingula ovata, M'Coy ? 



1816. Lingula ovata, M'Coy, Synopsis Silur. Foss. Ireland, p. 24, pi. iii, fig. 1. 



1866. Lingula ovata, M'Coy, Davidson, Mon. Brit. Foss. Brack., vol. iii, pt. vii, p. 38, pi. ii, fig. 19 

 (1 figs. 20-23). 

 Non 1883. Lingula ovata, M'Coy,. Davidson, op. cit., vol. v, Silur. Suppl., p. 207, pi. xvii, fig. 25. 



It is doubtful if this species really occurs in the Girvan area, but some poor 

 specimens from the Whitehouse Beds may perhaps be attributed to it. Their state 

 of preservation renders a precise determination impossible. 



Horizon. — Whitehouse Group. 



Locality. — Whitehouse Bay, Shalloch Mill. 



Lingula pseudoquadrata, sp. nov. 

 (Plate II, figs. 17, 18.) 



Shell subquadrate, length to width about 3 : 2, widening slightly anteriorly ; sides 

 subparallel ; anterior end abruptly truncate, nearly straight ; shoulders short, making 

 large obtuse angle at beak. Pedicle-valve somewhat flattened, with pair of low 

 straight rounded diverging ridges running forwards from beak to anterior lateral 

 angles of valve ; beak slightly raised, with small steep area below it crossed by 

 triangular pedicle-slit or groove. Surface of valves marked by rather coarse concentric 

 lines and growth-ridges of unequal strength. 



Dimensions. — Length of valve about 7 '5 mm. ; width of valve about 5'0 mm. 



Horizon. — Balclatchie Group. 



Locality. — Dow Hill. 



Remarks. — It may be considered doubtful whether this form is not the young 

 of some species, but I cannot discover any shell on the same horizon which can 

 be regarded as its adult representative. Of various species L. quadrata comes nearest 

 to it, but I have no certain evidence that this occurs in the Balclatchie Beds. The 

 pair of low ridges diverging to 'the anterior lateral angles are distinctive, and are 

 certainly not due to any distortion or accident of preservation. 



* M'Coy, Syn. Silur. Foss. Irel., p. 24, pi. iii, fig. 1. 



