250 Prof. T. Rupert Jones and J. W. Kirkby— 



carapace is fully as high at one end as the other, the curve of the 

 posterior extremity forming a more obtuse angle with the ventral 

 margin, which is but slightly convex. The general outline is thus 

 more subquadrate than in the others. 



Var. c. Fig. 8. 



This is very like Beyrichia arcuata (Bean) in appearance, and we 

 were at first disposed to keep it apart from the present species, for it 

 shows no indications of the two stout ribs along the centre of the 

 valves, but it possesses the sharp dorsal rib or crest in full force. 

 This latter feature, and similar ventral overlap by the right valve, 

 together with the way in which the ribs become nearly obsolete in 

 other examples of variabilis, cause us to group it with this species. 



From the number of specimens of this species obtained from the 

 shale of the boring, it would appear to have been of gregarious 

 habit. Most of the specimens are single valves. 



2. Kikkbya plicata, Jones and Kirkby. Plate VII. Figs, la, lb, 



2, 3a, 3b. 

 K. plicata, J. and K. 1867, Trans. Geol. Soc. Glasgow, vol. ii. p. 221. 

 K. plicata, J. and K. 1885, Ann. Mag. Nat. Hist. ser. 5, vol. xv. p. 184, pi. iii. 

 fig. 9, 10«, b. 



Valves of this species are not rare among the Gayton Ostracods. 

 They differ a little from typical specimens ; their outline is more 

 nearly oblong, the dorsal and ventral margins being almost parallel, 

 and the ends nearly alike. The two longitudinal ribs that traverse 

 the central portion of the valve are well marked, slope upwards 

 posteriorly, and are looped together forward (in most examples). The 

 subcentral pit or constricted sulcus is deep and placed anteriorly. 

 One of the specimens shows a finely reticulated surface; all the 

 others we have examined are smooth. The shell is thick ; and the 

 length about -^ inch. 



K. plicata is not a common species. It was first found in Car- 

 boniferous Limestone, at Backwell, Charterhouse, and Weston-super- 

 Mare, in Somerset. It has not been noticed elsewhere in England. 

 In Scotland it occurs at various localities of the Calciferous-Sandstone 

 Series ; and very rarely in beds in the lower portion of the Carbon- 

 iferous-Limestone Series. 



3. Btthooypkis sublunata, Jones and Kirkby, MS. Plate VII- 



Figs. 9a, 9b, 9c, 10, 11. 



This is a species well known to us, though as yet undescribed. 

 It was first sent us by Mr. James Bennie (Geological Survey of 

 Scotland), in a washing of shale from Staneshiel Burn, Roxburgh- 

 shire ; also from another shale, at Tweeden Burn, in the same 

 county. Both these localities are in the Calciferous-Sandstone 

 Series. The species may be briefly described as follows : — 



Carapace subtriangular or lunate in outline ; tumid : with left 

 valve overlapping the right all round. Dorsal margin boldly and 

 almost evenly arched ; ventral margin straight or slightly convex ; 



