44 BRITISH DEVONIAN BRACHIOPODA. 



Spec. Char. Transversely oval, or suborbicular ; hinge-line much shorter than the width 

 of the shell ; cardinal angles rounded ; beaks more or less approximate, and considerably 

 incurved. Ventral valve gently and evenly convex, rarely exhibiting any mesial elevation. 

 Dorsal valve rather deeper than the opposite one, uniformly convex, pr presenting a shallow 

 longitudinal depression, apparent only in the proximity of the front, or extending to the 

 extremity of the beak. Area small, with lateral margins obscurely defined; fissure 

 triangular, partially covered by a pseudo-deltidium. Surface of both valves marked by 

 numerous concentric ridges, rarely more than a line apart in any place, but usually very 

 much closer, and from which projected numerous closely packed spines, forming a series 

 of spiny fringes overlapping each other all over the shell. Proportions variable. 



Length 12, width 13, depth 8 lines. 



Obs. Specimens which appear to agree in shape with Martin's Sp. lineata have been 

 found in the Middle Devonian limestone of Woolborough Quarry, near Newton Abbot 

 (fig. 13) ; while other examples are described and figured by Phillips under the same 

 denomination, from the Upper Devonian beds of South Petherwin and.Landlake (figs. 14, 

 15). In the specimens I have been able to examine, the outer shell-surface was very 



Mr. Jukes, on the other hand, informs me that an exploration in North Devon, in 1862, showed him 

 that the red and green slates and sandstones of Morte Bay were precisely like the " Upper Old Red " beds 

 of the western part of Cork, and the section above them, round Baggy Point into Croyde Bay, exactly like 

 the section which always comes above the Upper Old Red in West Cork. He can have no doubt, then, that 

 the beds at the southern end of Morte Bay are the Upper Old Red, in which no trace of a marine fossil has 

 yet been found, either in North Devon or South Cork. He also says that he could see no stratigraphical 

 reason for believing that the Petherwin beds were above or below the Pilton beds. The Pilton beds rise 

 from underneath the Coal-measures on the north and the Petherwin beds on the south, without .any 

 evidence, so far as he could see, of any unconformability between the Coalmeasure-slates above and the 

 others below in either locality ; neither was the lithological difference between the beds at the two localities 

 very striking, nor greater than might naturally occur in a distance of twenty-five miles. This intervening 

 distance is occupied by a very disturbed basin of crumpled Coal-measures, which also greatly resemble the 

 Coal-measures of the south of Ireland. 



The Middle Devonian of the Eifel would, anyhow, be represented in England by the Plymouth, Wool- 

 borough, Torquay, Dartington, and other similar deposits, and may, perhaps, be susceptible of being divided 

 into several horizons. At Torquay we would, according to Mr. Salter, have the Spirifer-sandstone group of 

 the Rhine ; in other places we certainly have the Stringocephalen-Kalk and Calceola-Schiefer or Lenne- 

 Schiefer (Eifel-Kalk of the Prussian geologists). The Lower Devonian Mr. Salter considers to be, perhaps, 

 the equivalent of the Old Red Sandstone; the " Tilestones," or Ledbury Shales, being, according to his 

 views, the Lowest Devonian. 



Mr. Pengelly informs me that, if the entire Siluro-Carboniferous interval is represented by the 

 Old Red Sandstone, as Mr. Jukes would appear to hold, it will follow, he thinks, that the Devonshire 

 lower slates, i. e. those below the Torbay, Newton, and Plymouth limestones, are the only Devonian beds 

 we have, all above being Carboniferous ; and that, should Mr. Jukes carry out his threat of handing 

 over to the Carboniferous system the Upper Old Red, the lower slates must go too, as he believes them 

 to be on the same horizon. Mr. Pengelly's impression, however, is that the Old Red Sandstone represents 

 the Lower, and the Devonshire or Damnonian beds the Upper, Devonian Period, or Siluro-Carboniferous 



