20 THE BRITISH CONULARLE. 



appearing either as black lines, flnsli with the surface, or as shelly ridges, rendered 

 prominent on the outside by the compression of the shell. Often the shell is 

 entirely flattened, so that the " septa " from the under faces are seen through the 

 shell of the upper face (PI. I, fig. 6 a). 



The ornamentation varies considerably, both in coarseness and in the arrange- 

 ment of the tubercles. The transverse ridges may be only about 40 per 5 mm., or 

 may be as many as 100. Again the same variety in arrangement is seen as is 

 described by Lindstrom for G. bilineata — ?'. e. the tubercles are sometimes close 

 together, forming a very definite tuberculated ridge (PL I, fig. G c), while in 

 other cases they are about equally spaced, laterally and vertically, and the actual 

 ridges are hardly seen (PI. I, fig. 7) ; again, in the same specimen the tubercles are 

 sometimes round, sometimes distinctly elongated (PI. I, fig. c). 



Affinities. — This species, together with C. punctata and G. sp. cf. asjiersa, form a 

 well-defined group, characterised by the presence of the paired " septa." They are 

 readily distinguished by this from all other forms, and are possibly related to 

 G. tenuis from the Carboniferous rocks, which shows the single central "septum." 

 The type of ornamentation is that seen in G. cxquisita, Barrande. 



Horizon and Locality. — Lower Ludlow Shales: Church Hill, Leintwardine ; 

 Bow Bridge, etc. Silurian : Gotland. 



Type. — Vetenskaps Akademi, Stockholm. 



Conularia punctata, sp. nov. Plate I, figs. 10 — 12. 



Diagnosis. — Shell of medium size, moderately thick, tapering uniformly. Cross- 

 section oblong, with the shorter diameter four-fifths of the longer. Faces equal 

 in pairs, flat; apical angles about 14° and 10° respectively (P). Marginal grooves 

 wide and shallow ; centre of face marked by a pair of internal ribs converging 

 towards the apex. Aperture, apex, and apical septa unknown. Ornamentation 

 inconspicuous; ridges fine, closely packed (40 in 5 mm. in adult shell), arched 

 across the face, and undisturbed by the central ribs ; studded with small tubercles 

 which tend to blend with those above and below, giving rise to vertical as well as 

 transverse striation. Furrows very narrow. 



Dimensions. — Length of one incomplete portion, 50 mm. Width of face, 32 mm. 



Description. — There are only four examples of this species, all in Mrs. Gray's 

 collection of Girvan fossils, and none are perfect. One small example (PI. I, 

 fig. 10 a) shows four faces at right angles to one another, and one pair appear 

 to be distinctly shorter than the other pair (PL I, fig. 10 1>). This is the only 

 specimen in which the cross-section can be directly ascertained, and this may be 

 misleading, as the preservation is not good. The longitudinal " septa " are well 

 seen, both as black lines on the exterior (PL I, fig. 10 a), and as projecting ribs on 

 the inner face (PL I, fig. 11). They appear to be solid cores between the two 



