30 THE BRITISH CONULARLE. 



double the shorter. Faces equal, slightly convex; apical angle 17° — 20°. 

 Marginal groove of medium depth, base rounded; facial grooves absent. Apical 

 septum flat. Ornamentation fine; ridges fairly close (average 18 in 5 mm.), 

 forming an angle of 145° across the face; point of angulation nearer to the 

 "central" than to the "lateral" marginal groove; ridges continuous across the 

 grooves, at the base of which they form an angle of almost 180°; studded with 

 small, rounded, widely separated tubercles. Furrows crossed by narrow, well- 

 defined vertical bars. 



Dimensions. — Length, 40 — 50 mm. Greatest width of face, 16 mm. 



Description. — Well-preserved examples of this small species are obtained from 

 Thraive Glen, but those from Woodland Point are all somewhat fragmentary. The 

 figured specimen shows a nearly perfect apical septum, which, unlike the septa of 

 most species, is quite flat ; and since the surface is quite unwrinkled, this must be the 

 natural form. The small oblong projection in the centre is very suggestive of 

 some sort of siphuncle (PI. V, fig. lb). I have not seen anything resembling 

 this in any other example, even where the septa are nearly perfect. In this 

 specimen the central tube appears to be closed, and may very likely be only a scar 

 left by the final completion of the septum. 



Affinities. — This species resembles most closely C. cesicularis, from which it is 

 distinguished by the large angle of the face, the flat apical septum, and slight 

 differences in the ornamentation. 



Horizons and Localities. — Upper Bala and Middle Llandovery : Thraive Glen 

 and Woodland Point, Girvan. 



Type. — Mrs. Gray's Collection. 



Conularia vesicularis, sp. nov. Plate V, figs. 3 — 6. 



Diagnosis. — Shell of medium size, tapering uniformly. Cross-section at the 

 aperture a rhomb with diameters nearly equal, at the apex an ellipse or the figure oo. 

 Faces equal, flat, convex, or gently concave near the aperture ; apical angle 10° — 11°. 

 Marginal grooves of medium depth ; facial grooves absent. Apical septa convex. 

 Ornamentation fine; ridges moderately close (average 17 in 5 mm.), forming an 

 angle of 140° across the face; the point of angulation slightly nearer to the " central " 

 than to the "lateral" marginal groove; ridges continuous across the marginal 

 grooves and forming an angle at the base of about 150°. Ridges studded with 

 rounded tubercles ; furrows crossed by prominent bars. 



Dimeiisions. — Length about 90 mm. Greatest width of face, 14 mm. 



Description. — This species is of widespread occurrence in the uppermost 

 Ordovician rocks. Specimens are not usually well preserved and no aperture is 

 known. The " central " marginal groove is usually deeply sunken towards the 



