Carboniferous Ostracoda from the Gay ton Boring. 251 



extremities pointed and nearly alike, though the posterior is rather 

 the most acute ; seen from above ovate, with the greatest diameter 

 rather behind the centre. Within and a little below the margin of 

 each valve a thin sloping ledge or plate projects inwards, and is 

 most developed at the extremities (Fig. 10) ; surface smooth (finely 

 polished in examples from Staneshiel Burn) ; shell thick ; length 

 •sV inch. 



We refer this species to Bythocypris doubtfully. The over- 

 lapping valve appears to be the left, but it is difficult to speak with 

 decision on this point, both in this case as well as in some other 

 Carboniferous species. Were the right valve the largest, then 

 Macrocypris would apparently be the better genus in which to 

 place it. 



It is a comparatively common form among the Grayton Ostracods, 

 occurring both as single and united valves. Individuals show some 

 differences in relative length and height. Fig. 11 represents one 

 of the longest of them, and rather suggests relationship with 

 another Lower-Carboniferous species — Argillcecia cequalis, J. & K. MS. 



Cythere? lunata, J. & K. (undescribed), from the Carboniferous 

 Limestone of Holwell, Somerset, has some resemblance to the pre- 

 sent species, though larger ; and it may probably be a related form. 



4. Macrocypris Jonesiana, Kirkby. Plate VII. Fig. 12. 



Bairdia Jonesiana (Kirkby), 1859. Ann. and Mag. Nat. Hist. ser. 3, vol. ii. 

 p. 432, pi. xi. figs. 1, 2. 



Fig. 12 represents a specimen that comes nearer to this species 

 than anything else we know. The dorsal margin is not so regulai'ly 

 arched as in B. sublunata, the posterior slope being longer and 

 flatter than the anterior ; and the anterior extremity is broadly 

 rounded, while the posterior is subacute. We refer it to M. Jonesiana, 

 with some doubt. 



5. Cytherella extuberata, Jones and Kirkby. Plate VII. Figs. 

 13a, 136, 13c, 13d. 



Leperditia Okeni (Miinster), var. extuberata, J. & K. 1880, Quart. Journ. Geol. 

 Soc. vol. xxxvi. p. 588. 



This species was discovered by one of us several years ago in the 

 Calciferous Sandstones of Fifeshire. It was then considered to 

 belong to Leperditia, and to be probably a variety of the common 

 Carboniferous species, L. Okeni (Miinster). This opinion was arrived 

 at by a study of specimens imbedded in the matrix, only partially 

 showing external characters, and by our taking the straight edge as 

 the uppermost or dorsal margin. 



Some years after this we received examples of the same fossil 

 from our friend, Mr. James Bennie, who collected them from the 

 Calciferous-Sandstone shale, at Staneshiel Burn, already mentioned. 

 These specimens were, in many cases, single valves, finely preserved, 

 showing the interior ; and from these it is evident, owing to one 

 valve being much larger than the other, and from it having an 

 internal marginal groove for the reception of the smaller valve, that 



