932 DR F. R. C. REED ON THE 



Strichlandinia lirata (Sowerby), var. nov. scotica. 



(Plate XXIII, figs. 1-4.) 



1883. Strichlandinia lirata (Sowerby), Davidson, Mon. Brit. Foss. Brack., vol. v, Silur. Suppl., p. 165, 



pi. ix, fig. 1. 

 1883. Strichlandinia lens (Sowerby), Davidson (pars), ibid., p. 165, pi. ix, figs. 2, 3 (non figs. 4, 5). 



This variety is distinguished from the type-form # by possessing low rounded 

 radial plications, fewer in number and less distinctly marked. In shape it is oval to 

 subcircular and not transverse, the hinge-line is always considerably less than the 

 maximum width of the shell, and the cardinal angles are well rounded. The variety 

 grows to a large size, some shells measuring over 50 mm. in length. Davidson figured 

 some of these shells as Strickl. lens, and in some specimens the radial plications are so 

 faint that the resemblance is great. The shape of the shell, moreover, is that of the 

 typical Str. lens. The interior is not well seen in any of the specimens. There are 

 usually fairly well-marked concentric growth-ridges on the surface with finer con- 

 centric lines between them, but these concentric markings are subordinate to the radial 

 plications. From Str. mullochensis this variety differs in the stronger radial plica- 

 tions as well as in the shape of the shell and length of the hinge-line. The doubtful 

 examples from Newlands furnish a connecting link. The species described by 

 Gagel t as Strickl. Schmidti, Kiesow, is very closely allied, but seems to have no 

 radial plications on the fold. 



Horizon. — Saugh Hill Group. 



Localities. — Woodland Point, ? Newlands. 



Strichlandinia mullochensis, sp. nov. 

 (Plate XXIII, figs. 5-8.) 

 Shell transverse, wider than long, widest at hinge-line ; cardinal angles less than 

 right angles or subrectangular, very slightly rounded. Pedicle-valve gently convex ; 

 beak small, pointed, slightly incurved, rising above hinge-line ; hinge-area narrow ; 

 surface of valve with narrow rounded shallow median sinus widening slightly towards 

 the front ; interior with small spondylium supported on short septum extending a 

 little in front of it. Brachial valve gently convex, with small pointed incurved beak 

 and narrow triangular hinge-area ; surface with narrow rounded median fold ; interior 

 with very short closely placed socket-plates produced into small crura, and with 

 narrow linear faint median muscle-scar; ovarian areas coarsely pitted and extending 

 nearly to cardinal angles. Surface of both valves covered with strong low concentric 

 sublamellose growth-ridges, and generally with faint low irregular radial undulations. 



Dimensions. — 



(1) (2) (3) 



Length .... 28 21 18 mm. 



Width .... 40 24 24 mm. 



* Davidson, Mon. Brit. Foss. Brack., vol. iii, pt. vii, p. 159, pi. xx figs. 1-13. 



t Gagel, Brack, cambr. silur. Gesch. ()st-We,st Preussens (Konigsberg, 1890), p. 61, t. iv, fig. 9. 



