CONULARIA LAEVIGATA. 17 



Description. — This . species was instituted by Holm for the reception of a 

 small specimen from the Chasmopskalk (= Llandeilo) of Alleberg, Vestergotland. 

 Its existence in Britain has not, until now, been recorded, but there are nearly 

 thirty examples in Mrs. Gray's Girvan Collection. Portlock's G. quadri sulcata, 

 var. Silurian (Mus. Pract. Geol., reg. no. 12645), is also, undoubtedly, an 

 example of this species, which is therefore represented in both Scotland and 

 Ireland. 



Some of the Scottish specimens are quite well preserved ; most are flattened, 

 but one (PI. I, fig. 1), shows approximately a square cross-section, and this is 

 probably the natural form, though Holm's type from Alleberg is slightly com- 

 pressed. In the latter specimen also there appears to be a slight inequality 

 between the pairs of faces, but this is not noticeable in the British forms. 

 In close juxtaposition with the examples from Craighead there occur, in more 

 than one case, rods covered with a shell exactly similar to that of the Gouularise, 

 and tapering from a width of 3 mm. to that of 1 mm. I have seen none actually 

 attached to the Qonularia, but I think it highly probable that they constitute the 

 apical end of the shell, which was drawn out to a considerable length, and was 

 probably attached to some foreign substance. The longest has a length of 2-5 mm. 



Affinities. — This species is quite different from any other British form. It 

 resembles, in some characters, the Swedish C. Imvis (Lindstrom), but is readily 

 distinguished by the horizontal growth-lines. 



Horizon and Locality. — Llandeilo : Craighead, Ardmillan, and Balcletchie, 

 Girvan. Lower Silurian : Desertcreat, Co. Tyrone. 



Type. — Geological Survey Collection, Stockholm. 



Conularia laevigata, Salter. 



I860. Conularia laevigata, J. W. Salter, in Ramsay's Geol. N. Wales, Mem. Geol. Surv., vol. iii, ed. 1, 

 p. 354, woodc. 19 (also ed. 2, 1881, p. 562). 



Diagnosis. — Shell small, tapering uniformly; cross-section rhombic (?). The 

 faces meeting at one acute angle slightly smaller than the other pair; slightly 

 convex apically and concave aperturally ; apical angle 7° — 8°. Marginal grooves 

 shallow, rounded ; facial grooves absent. Aperture, apex, and apical septa unknown. 

 Ornamentation absent, except for gently curved irregular lines of growth. 



Dimensions. — Length 40 — 50 mm. Width of face 14 — 15 mm. 



Description. — Only the type specimen of this species is known. It is somewhat 

 doubtful whether the inequality of the sides referred to by Salter is not due to 

 accident, and the course of the growth-lines (i. e. rising to a maximum at the angle 

 where the smaller sides meet) may also be a secondary character. 



Affinities. — This species differs from the other smooth types in the absence of 



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