BRITISH SILURIAN BRACHIOPODA. 201 



129. Rhynchonella Scotica, Bav. Sil. Sup., PI. XI, fig. 26. 



Shell marginally nearly circular, or about as broad as long; dorsal valve very 

 convex, gibbous at the umbo, geniculated near the front and lateral margins, fold wide, 

 commencing to rise at the anterior half of the valve ; ventral valve convex with a wide 

 mesial sinus, beak much incurved and coming almost in contact with the umbo of the 

 opposite valve. Posterior half of both valves smooth. Anterior half of each valve 

 covered with some twelve ribs, of which four occupy the fold, three the sinus. A dark 

 line proceeding from the beak and umbo along the middle to the valves to some distance 

 show that a septum is present in the interior of both valves. 

 Length 5, breadth 5, depth 4 lines. 



Ohs. — This is a globular little form, remarkable from the presence of a septum in 

 both valves. It was procured by Mrs. R. Gray from the Llandeilo, at Craighead, in 

 Ayrshire. 



130. Rhynchonella Peachi, Bav. Sil. Sup., PI. XI, fig. 25. 



Shell marginally sub-pentagonal, longer than wide ; valves moderately convex. In 

 the dorsal valve a wide mesial fold begins to rise at about half its length. In the 

 ventral valve the sinus also commences at about half the length of the valve. The 

 posterior half of the valves are smooth, the anterior half of each valve is ornamented 

 with nine angular ribs of which three occupy the fold, two the sinus. 

 Length 7, breadth 6^, depth 5^ lines. 



Ohs. — This form differs from B. Scotica in being larger, longer than wide, and 

 subpentagonal in shape. It was procured by Mrs. R. Gray from the Llandeilo at 

 Craighead, Girvan. I have named it after Mr. C. W. Peach of the Geological Survey 

 of Scotland. 



Rhynchonella, sp. Sil. Sup., PI. XI, fig. 24. 



Obs. — Several specimens of this Hhyncltonella have been collected by Mrs. R. Gray 

 from the Llandeilo at Minuntion, in Ayrshire. It has puzzled me much on account of 

 its near resemblance to some Upper-Llandovery forms of Eh. nucula as well as of B 

 Bayi. I have preferred not to give it a name, and notice it here for the sake of refer- 

 ence, and as adding another form to the many that occur in the Llandeilo of Scotland. 



