32 THE BRITISH CONULARLE. 



simple curves across the face, continuous across the marginal groove, studded 

 with small, round, well-spaced tubercles. Furrows marked by secondary 

 transverse ridges and faint longitudinal striatums — the latter especially marked 

 close to the marginal grooves. 



Dimensions. — Length sometimes as much as 70 mm., usually 20 — 30 mm. 

 Greatest width of face, 20 mm. 



Description. — This is a well-marked species, of which there are several 

 examples in Mrs. Gray's Collection. The most characteristic features are the 

 broad sweeping curves which the ridges make across the face, the secondary 

 transverse ridges, and the small distant tubercles. 



Affinities. — This species is easily distinguished from other cancellate forms by 

 the square cross-section and fine curved ridges. With 0. crassa it forms a 

 transition between the Monilifera3 and the Cancellatse. 



Horizon and Locality. — Upper Bala (Starfish Bed) : Girvan. 



Type. — Mrs. Gray's Collection. 



Conularia crassa, sp. nov. Plate IV, figs. 4 — G. 



Diagnosis. — Shell large, tapering uniformly ; cross-section a square, with the 

 sides gently convex. Faces equal, convex ; apical angle about 10°. Marginal 

 grooves very shallow, wide ; facial groove hardly perceptible. Aperture, apex, 

 and apical septa unknown. Ornamentation coarse ; transverse ridges strong, 

 widely separated (5 — 6 in 5 mm.), forming an angle of about 140° down the 

 centre of the face, studded with large rounded, distant tubercles (8 in 5 mm.). 



Dimensions. — Length at least 120 mm. Greatest width of face, 24 mm. 



Description. — Examples of this species are found in a fairly good state of 

 preservation, often retaining a considerable portion of the shell. They have 

 usually undergone flattening, so that the cross-section is obscure, but one 

 specimen (PL IV, fig. 5) shows a broad ellipse, which appears to have been 

 derived from a square, the sides of which are replaced by gently convex 

 curves. The most marked character of the species is the exceedingly wide and 

 shallow marginal grooves, which are of the nature of gentle undulations, without 

 any well-marked boundaries. The ornamentation is continued across them 

 without any break. The appearance of the ridges varies with the state of 

 preservation. Sometimes the blunt, rounded tubercles are clearly seen ; but more 

 often they appear flattened and pierced in the centre (PI. IV, fig. h) ; or, again, 

 only a raised, wavy ridge may be seen (PL IV, fig. 4 b) ; or, lastly, the tubercles 

 may be worn away and represented by hollows, between which little portions of 

 the shell still remain. The furrows are crossed by very slight, inconspicuous and 

 inconstant vertical undulations. 



