CONRADELLA SLADENSIS. 45 



diameter of the shell, with centre situated at less than half the height. Outer 

 whorl with swollen rounded sides, broadest at base;, umbilical edge subangular ; 

 umbilical slope steep, short, abrupt ; dorsum with high, narrow, suddenly elevated 

 prominent carina bearing slit-band having sharp edges and strong distinct lunula. 

 Surface of shell crossed by numerous sharp, regular, concentric imbricating 

 lamellae, equidistant and finely fimbriated, meeting carina nearly at right angles ; 

 interspaces with very delicate revolving interrupted lines. 



Dimensions. — Height of shell, 14 — 15 mm. 



Horizon. — Middle Ordovician : Whitehouse Group. 



Locality. — Shallocli Mill, near Girvan. 



Remarks. — We may compare this species with G. triangular is, Ulrich and 

 Scofield,^ and C. fimhriata, Ulr. & Scof.^ The lamellee are less numerous, more 

 coarsely fimbriated, and further apart than in the form described below as 

 Conradella ? mnltilineata, sp. nov., from the same Girvan beds, but otherwise the 

 species seem allied to each other. The type specimens are in Mrs. Gray's 

 Collection. 



2. Conradella sladensis, sp. nov. Plate IX, fig. 2. 



1906. Conradella ? sp., Eeed, Geol. Mag. [5], vol. iii, p. 367, pi. xx, figs. 5, 5a, 5b. 



Specific Characters. — Shell of few whorls, coiled in the same plane; whorls 

 higher than wide, carinated, with upper portion compressed, lower portion swollen, 

 with rounded inflated sides. Umbilicus small ; umbilical slope steep, short, 

 rounded. Carina elevated and occupied by slit-band, crossed by rather distant 

 strong lunulje. Sides of whorls ornamented by rather coarse raised fimbriated 

 lines, equidistant and equal in size, curving back in a gentle sigmoidal manner to 

 meet the slit-band at about 75°, and connected by less prominent, short, straight 

 lines at right angles to them and alternately arranged, not forming continuous 

 revolving spirals but making a fairly regular honeycomb pattern. 



Dimensions. — Height about 6 mm. 



Horizon. — Upper Ordovician : Slade Beds. 



Localitij. — Upper Slade, Haverfordwest. 



Remarks. — No better examples of this small shell have been discovered than 

 those described in 1906, from which the above diagnosis has been drawn up. As 

 then remarked, this species seems allied to Conradella, thjeri var. cellulosa, Ulrich,^ 

 but the keel seems to be more elevated and the inner whorls less exjjosed. We 

 may distinguish our species by the name C. sladensis. 



1 Ulrich aud Scofield, op. cit., p. 908, pi. Ixvii, figs. 19—22. 



2 Ihkl, p. 907, pi. Ixii, fig. m ; pi. Ixvii, figs. 7—10. 



3 Ulrich aud Scofield, op. cit, p. 910, pi. Ixvii, figs. 27 — 29. 



