282 CARBONIFEROUS LAMELL1BRANCHIATA. 



Observations. — None of the species of Sedgwickia described by M'Coy seem to 

 possess the characters of the shells from Redesdale. I have therefore been obliged 

 to establish a new species for them. More gibbose and less transverse than 

 S. gigantea, 8. ovata is even less like the subquadrate form of 8. scotica, and it is 

 easily separated from 8. suborbicularis by its larger size and its characteristic 

 contour. 



S. ovata is fairly plentiful at Redesdale, but is often badly preserved : figs. 

 8—10, PI. XXVI, are from this locality, and fig. 11, PI. XXVI, from the famous 

 Scorpion-beds of Grlencartholme, Dumfriesshire ; the latter locality is supposed to 

 be at a much lower horizon than the Redesdale Ironstone, and is placed in the 

 Calciferous Sandstone series. It is interesting to note that the species also 

 occurs in the same series of the east of Scotland. 



I have been able to isolate the hinge in one specimen, and this shows distinctly 

 that the right valve has a small single cardinal tooth, fig. 1 a, PI. XXVII. M'Coy 

 states that the genus Sedgwickia is edentulous, but figures no specimens ; and 

 although I cannot affirm that any other species of the genus has a tooth in its 

 hinge, it is possible that, owing to its very small size, this character may have 

 been overlooked, and it would appear from the cast of 8. gigantea, PL XXVI, fig. 3, 

 that that species at least was edentulous. 8. ovata is much more ovate and trans- 

 verse than 8. scotica, and appears not to attain to so large a size. The diagonal 

 ridge is not so well marked, and the posterior end is narrower and less truncate. 



Mr. Kirkby has, I think, identified specimens of this species which occur in 

 the Encrinite-bed of Mr. Brown, east of Pittenweem Harbour, with Leptodomus 

 costellatus, M'Coy (op. supra cit.). I have myself collected from this bed, and 

 have found Sedgwickia ovata there, but not the other shell. If only the anterior 

 part of the shell be seen the mistake is easily made. I am strengthened in this 

 opinion by drawings of the shell in a MS. book, kindly lent me by Mr. Kirkby, in 

 which a very typical example of Sedgwickia ovata is called Leptodomus costellatus. 



S. ovata has somewhat the shape of S. bullata, M'Coy, but the elevated ridges 

 on the front of the shell are very few and far apart in the latter species. The 

 figure shows only half a dozen ; and I think that this shell may possibly be the 

 Edmondia Josepha of the West of Scotland ; but I hesitate yet to give it as a 

 synonym. None of the other species of Sedgwickia which I have been able to 

 examine have so few concentric ridges anteriorly. 



The original description of 8. bullata is as follows : — " Transversely oblong, 

 very gibbous, length about two thirds the width ; anterior side short, rounded ; 

 hinge-line nearly as long as the shell is wide, posterior end slightly oblique, 

 subtruncate ; beaks very large, tumid ; an obtusely rounded ridge from the beak 

 to the posterior angle ; anterior side with strong rounded distinct ridges ; middle 

 of the shell and posterior side smooth." 



