906 DR F. R. C. REED ON THE 



triangular specimens were labelled by Davidson Str. shallochensis, though he only 

 recorded this species ((7*. cit., p. 192) from Shalloch Mill in the Girvan area. It 

 undoubtedly resembles the Corwen shells also referred to Str. shallochensis by 

 Davidson and figured under this name by him, but the cardinal angles in Str. 

 valens are usually more pointed, and the difference in the strength of the radii is less 

 marked. ( )ur Str. deficiens from Balclatchie is a near relative, and so is Str. sim ulans, 

 M'Coy, while several American species (e.g. Str. flitexta, Hall) appear to be allied. 



Genus Schuchertella, Girty. 



Schuchertella applanata (Salter). 



(Plate XIX, figs. 18-20.) 



1846. Ort/iisl applanata, Salter, Appendix to M'Coy's Syn. Silur. Foss. Ireland, p. 72, pi. v, fig. 1. 



1865. Strophomena applanata (Salter), Haswell, Silur. Form. Fentlands, p. 34, pi. ii, fig. 18. 



1868. Strophomena applanata (Salter), Davidson, Trans. Geol. Soc. Glasgow, vol. i, p. 19, pi. ii, 



figs. 19, 20. 

 1S70. Strophomena applanata (Salter), Davidson, Mon. Brit. Foss. Brack., vol. iii, pt. vii. p. 308. 



pi. xliii, figs. 12-14. 

 1883. Strophomena applanata (Salter), Davidson, ibid., vol. v, Silur. Sujpl., p. 226. 



This species was recorded by Davidson in his Supplement from Penkill, Bargany 

 Pond Burn, and Cuddystone Glen in the Girvan district. These specimens are all 

 small, not exceeding 22 mm. in width, and they agree with the typical form from 

 the Wenlock Shale of the Pentland Hills, but the species was originally described by 

 Salter from Cong in Ireland as Orthis, with a query. The projection of the main 

 ribs on the margin is not marked, and a few very oblique short corrugations arc 

 frequently present along the hinge-line, meeting it at very acute angles. Tin 

 internal characters, so far as they are preserved, indicate its close resemblance to 

 Soli, pecten, Linn. 



Horizons. — (l) Penkill Group; (2) Camregan Group; (3) Saugh Hill Group. 



Localities. — (1 ) Penkill ; (2) Bargany Pond Burn, Cuddystone Glen ? ; (3) Newlands. 



Schuchertella '. incxpectata, sp. nov. 



(Plate XIX, figs. 21, 22.) 



Shell semielliptical, compressed, flattened; hinge-line equal to or slightly 

 than maximum width of shell ; cardinal angles rectangular or slightly rounded. 

 Pedicle-valve nearly flat; beak small, scarcely rising above hinge-line; bin 

 very narrow; interior of valve with small short triangular teeth and indistinct small 

 flabelliform contiguous diductor impressions. Brachial valve nearly fiat ; beak very 

 small; hinge-area linear; interior with thin laminar short transverse cardinal 

 process continued at sides into long thin crural plates making a very small angle 

 (l5°-20°) with hinge-line. Exterior of valves covered with 30-32 regular equi- 

 distant strong rounded straight radiating primary ribs of equal size, with wider 



