428 Prof. F. M'^Coy on some new Brachiopoda. 



very large quincuncially arranged punctures, usually about 

 twice their diameter apart ; rostral portion divided by a nar- 

 row slit left by the mesial septum, extending less than one 

 half the length of the shell. Width of large specimen 4i lines, 

 proportional length of receiving valve y^jj^^, depth -^-^-q. 



This species has much the form oi Leptcena [Chonetes) volva 

 (M'Coy), but is not so wide and is more gibbous : it is the only 

 carboniferous species I know at this date that has a smooth 

 surface. The measurements given above are from a large Irish 

 specimen in the collection from the limestone of Mount Rath, 

 the English ones being only 2 lines wide. 



Rare in the dark carboniferous limestone of Lowick, North- 

 umberland. 



(CoL University of Cambridge.) 



Leptcena [Chonetes) subminima (M'Coy). 



Desc. Rotundato-quadrate, length three-fourths or four-fifths 

 the width ; receiving valve very gibbous in the middle, greatest 

 depth a little behind the middle ; hinge-line as long as the 

 shell is wide, forming flattened ears, slightly acute from the 

 sigmoid outline of the sides, having three or four moderately 

 long slender spines on each side of the beak, extending back- 

 ward as usual in the plane of the margins; front margin 

 moderately convex ; surface uniformly covered with close ob- 

 tuse striae once or twice branched, but nearly uniform in size 

 on all parts of the shell, and so fine that twelve at the margin 

 only occupy half a line when decorticated, the impressed lines 

 between the strise of the surface very coarsely punctured, 

 and the beak slit by the deep impression of the mesial sep- 

 tum extending half the length of the shell; entering valve 

 nearly as concave as the receiving one is convex; surface 

 similar in both valves, the strise being crossed by fine close 

 lines of growth. Average width li line; the depth seems 

 about half the width. 



This little species is so extremely like the Silurian Leptana 

 minima that it required a comparison of the specimens to distin- 

 guish them, more especially as the spines on the hinge-line of 

 the present species are not often seen ; the carboniferous fossil 

 has more uniform and less branched striae, and they are so much 

 finer than in the Silurian species, that double the number is 

 uniformly found to occur in the same space of half a line near 

 the margin. It is possible that this may prove identical with 

 the LeptcEna gihherula of my volume on the ^ Mountain Lime- 

 stone Fossils of Ireland,^ t. 20. f . II (which certainly has no 



