910 DR F. R. C. REED ON THE 



front margin ; lateral portions high, swollen, subangular ; beak small, pointed, 

 scarcely incurved, with small triangular hinge-area below it. Brachial valve in- 

 flated, swollen, more convex than opposite valve, with broad rounded fold arising at 

 about half its length, and rising highest at front margin ; lateral lobes slightly 

 swollen, dependent; beak swollen, rounded, strongly incurved; interior with two 

 pairs of subcircular muscle-scars, and median septum nearly half the length of the 

 valve. Surface with regular close fine concentric lines (with traces of minute pits 

 between them ?). 



Dimensions. — Length, 10 mm. ; width, 11 mm. 



Horizon. — Stinchar Limestone Group. 



Locality. — Craighead. 



Remarks. — Some of these small shells were labelled by Davidson " Triplecia 

 maccoyana, Dav.," but they are quite distinct from that species, the type of which 

 came from Brynbedwog Quarry near Bala, # and Davidson does not record it from 

 Girvan in his list of species, t The nearest ally of our species appears to be TV. 

 nucleus, Hall,J from the Trenton Limestone. Tr. poloi (Martelli) § from the Ordo- 

 vician of China seems to be allied. Martelli || put the latter species, which is now 

 attributed by Weller to Triplecia, in the genus Porambonites, and the occurrence of 

 small pits on the Girvan shell would also suggest this generic reference. 



Triplecia woodlandensis, sp. nov. 



(Plate XX, figs. 8-16.) 



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

 pi. ix, figs. 16-18 (non figs. 10-15, 19-20, nee Pentamerus undatus, auctt.). 

 Non 1839. Atrypa undata, Sowerby, in Murohison's Silur. Syst., p. 637, pi. xxi, fig. 2. 



Shell subquadrate, rounded to transversely elliptical ; anterior margin subtruncate 



or lobate ; hinge-line less than width of shell ; cardinal angles rounded, obtuse. 



Pedicle-valve flattened on lateral portions, slightly swollen near beak, middle third 



occupied by broad concave sinus, rapidly widening anteriorly, with straight sharp 



angular margins, and concave floor produced as rounded tongue ; beak small, acute, 



slightly incurved, scarcely rising above hinge-line, with minute apical foramen ; 



hinge-area narrow, at right angles to valve, with wide triangular delthyrium ; diduc- 



tor muscle-scars separate, flabelliform, strongly divergent. Brachial valve convex, 



swollen, with beak much inflated and incurved, rising high above hinge-line and 



nearly touching beak of opposite valve ; well-defined broad median rounded fold on 



surface increasing anteriorly in height and width and rising steeply from lateral 



lobes ; muscle-scars very faint. 



* Davidson, op. cit, vol. iii, p. 199, pi. xxiv, fig. 29. 



+ Davidson, op. cit., vol. v, Silur. Suppl, pp. 224, 225. 



+ Hall, Palxont. N.Y., i, 1847, p. 138, pi. 33, fig. 2 ; Hall and Clarke, op. cit., Bracli., i, pi. xic, figs. 8, 9. 



§ Weller, Research in China, vol. iii, 1913, p. 281, pi. 25, figs. 7-9. 



|| Martelli, Boll. dell. Soc. Geol. Ital, vol. xx, 1901, p. 304, pi. iv, figs. 13-16. 



