900 DR F. R. C. REED ON THE 



crushed, shows a short subcircular muscle-scar, more deeply sunk and more sharply 

 margined than in the last-mentioned species, but otherwise the internal characters 

 are not preserved. 



Dimensions. — Length about 22"0 mm. ; width (on. hinge-line) about 2G'0 mm. 



Horizon. — Mulloch Hill Group. 



Locality.— Mulloch Hill. 



Genus Strophonella, Hall. 

 Strophonella euglypha (Hisinger). 



1819. Leptivna euglypha, Hisinger, Anted-, pi. vi, fig. 4. 



1870. StropJiomena euglypha (Hisinger), Davidson, Mon. Brit. Fans. Brack., vol. iii, pt. vii, p. 288, 

 pi. xl, figs. 1-5 (for further references). 



This species seems very rare in the Girvan district. There is one good interior 

 of a pedicle-valve from Woodland Point in Mrs Gray's collection, showing the 

 characteristic large diductor scars and other features of the species, and it seems 

 indistinguishable from typical Wenlock examples. Davidson does not record this 

 species from Girvan. 



Horizon. — Saugh Hill Group. 



Locality. — Woodland Point. 



Strophonella 'penkillensis, sp. nov. 

 (Plate XVIII, figs. 11-13, 14?) 



1883. Strophomena antiquata, Sowerby, Davidson (pars), Mon. Brit. Foss. Brack., vol. v, Silur. Suppl., 

 p. 193 (non pi. xv, figs. 12-14). 



Shell transverse, triangular, maximum width along hinge-line ; concavo-convex, 

 strongly resupinate ; cardinal angles flattened, acutely pointed at about 30°-45° ; 

 weak indefinite median fold present near anterior margin ; disc flattened, somewhat 

 obscurely marked off from anterior half, which is arched down ; hinge-line finely 

 crenulated. Pedicle-valve strongly concave ; beak small, pointed, not projecting, 

 inconspicuous ; hinge-area linear, narrow ; interior with pair of small teeth and short 

 transversely subcircular completely circumscribed muscle-scar, about one-fourth (or 

 less) the length of shell, composed of two flabellate broad shtfrt diductors, slightly 

 divergent, with narrow ridge between them anteriorly. Brachial valve with flattened 

 disc and cardinal angles; margin arched down and swollen into low fold in middle: 

 beak inconspicuous ; hinge-area very narrow, linear ; interior of valve with prominent 

 elevated large bilobed cardinal process, each lobe oval and grooved on inner face ; 

 crural plates long, straight, thick, at 30°-45° to hinge-line ; hinge-plate thiek ; 

 posterior adductors small, deeply sunk, subcircular ; anterior adductors longer, narrow, 

 parallel, suboval, undefined in front, but laterally with thickened edges. Surface of 

 shell marked with regular fine equidistant primary radii about 20-30 in number, with 

 interspaces occupied by 5-7 much finer thread-like equal radii, all crossed by delicate 

 concentric lineation. Occasionally a shorter secondary radius equal in strength 



