934 DR F. R. C. REED ON THE 



Pentamerus (Barrandella) undatus (Sowerby), var. nov. penkillensis. 



(Plate XXIII, figs. 9-13.) 



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



pp. 161, 225 (PenkiU and Penwhapple Glen). 

 1883. Pentamerus tjlobosus (Sowerby), Davidson (pars), ibid., p. 163, pi. ix, figs. 21-24 (non Atrypd 



globosa, Sowerby). 

 1883. Whitfieldia tumida (Dalman), Davidson, ibid., p. 224. 



Shell transversely elliptical, rounded, subglobose, very unequally biconvex. Pedicle- 

 valve swollen, uniformly convex, rarely with faint broad median flattened sinus near 

 anterior margin ; beak large, swollen, incurved over concave false area ; floor of sinus 

 produced anteriorly into short rounded tongue. Interior of pedicle-valve with low 

 short median septum about one-fifth to one-sixth length of valve, and small short 

 narrow spondylium beneath beak ; straight subparallel vascular markings radiating over 

 whole internal surface. Brachial valve very gently convex or flattened, with promi- 

 nent rounded median fold increasing rapidly in height and width to anterior margin, well 

 defined in front. Interior with pair of very short crural (?) plates diverging at about 

 G0°. Surface of shell smooth, except for a few concentric submarginal growth-lines. 



Dimensions. — Length, 15-17 mm. ; width, 23-25 mm. 



Horizons. — (l) PenkiU Group ; (2) Camregan Group. 



Localities. — (l) PenkiU, Penwhapple Glen ; (l) Bargany Pond Burn. 



Remarks. — This shell seems more allied to P. undatus than to P. globosus, but 

 differs from the typical P. undatus in the almost complete absence of a sinus on the 

 pedicle-valve. The true P. globosus (Sow.), # has a subcircular shape and a much 

 longer median septum. 



Genus Metacamarella, nov. 



Shell oval, biconvex. Pedicle-valve with low median fold near anterior end com- 

 posed of several longitudinal plications chiefly developed towards front end ; beak 

 high, incurved, with open delthyrium ; small false area on each side ; interior with 

 small subumbonal spondylium and short median septum. Brachial valve with lower 

 beak than opposite valve ; low median fold near anterior end, composed of several 

 longitudinal plications ; interior with pair of long recurved crura, pair of long parallel 

 median septa, and muscle-scars as in Parastrophia. Shell thick, fibrous, punctate 



externally. 



Metacamarella balclatchiensis (Davidson). 



(Plate XXIII, figs. 14-18.) 

 1883. Stricklandinia 1 balcletchiensis, Davidson, Mon. Brit. Foss. Brack., vol. v, Silur. SuppL, p. 166, 



pi. ix, figs. 27, 28, 29. 

 1894. Camarella 1 balcletchiensis (Davidson), Hall and Clarke, Palwont. Netv York, vol. viii, Brach., ii, 



p. 221. 



Shell elongated, oval to subpentagonal, widest across middle, somewhat truncated 

 in front, strongly biconvex. Pedicle-valve rounded, convex, more or less inflated, 



* Davidson, op. cit., vol. iii, p. 156, pi. xix, figs. 10-12. 



