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BRITISH DEVONIAN BRACHIOPODA. 



Lept^ena (?) nobilis, M'Coy. PI. XVIII, figs. 19—21. 



Lept^na (strophomena) nobilis, M'Coy. British Palaeozoic Fossils, p. 386, pi. ii A, 



fig. 8, 1852. 



Spec. Char. Transversely semicircular, usually wider than long ; hinge-line equal to 

 the width of the shell ; ventral valve uniformly convex and strongly arched ; ears slightly 

 projecting, rounded, and more or less sharply defined ; beak rounded ; surface ornamented 

 with twenty or more straight or somewhat flexuous narrow ridges or ribs, of about equal 

 thickness throughout, which radiate, and extend from the beak to the margin, leaving 

 wide interspaces between them, in the middle of which, and at variable distances from the 

 beaks, shorter ridges, but similar to the larger ones, are developed. The intervening spaces 

 are slightly concave, and crossed in a more or less zig-zag manner by deep; strong, 

 irregularly curved, concentric wrinkles, but not crossing the ridges, scarcely four in a 

 longitudinal space of three lines ; surface of ridges and furrows marked by very fine, 

 slightly irregular, longitudinal, distinct striae, nine in the sp^ce of one line ; area of 

 moderate width. Dorsal valve concave, following the curves of the opposite one, and 

 similarly sculptured. Dimensions variable. 

 Length 2 inches, width 3 inches. 



Obs. I have not been so fortunate as to procure perfectly preserved examples of this 

 fine shell, and therefore have taken some of the details of my description from those pub- 

 lished by Prof. M'Coy. The specimens which I have been able to examine were not 

 (as is the one figured by M'Coy) put out of shape by pressure, and showed that the shell 

 was regularly semicircular, and nearly resembling Leptcena inter strialis. I cannot go as 

 far as does Prof. M'Coy, when he affirms that " this fine species is so completely unlike 

 any other, that it is unnecessary to point out the distinctions." On the contrary, it will 

 require to be made certain whether L. nobilis might not be a full-grown condition of 

 L. inter strialis. The material at hand will not, however, enable me to determine this 

 point. It is also uncertain whether this shell should remain in the sub-genus Leptana, 

 the muscular arrangement of the ventral valve leading one to surmise the possibility of 

 its belonging to Strophomena or Strcptorgnchus. The ribs appear to be much coarser in 

 some specimens than in others ; and in certain examples not only are the interspaces 

 smaller, but one, two, and even occasionally three new ridges, equal in width to the 

 primary ones, are developed between the original ones. 



Lept. nobilis occurs in the Middle Devonian Limestone of Woolborough quarry, near 

 Newton Abbot, and, according to Prof. M'Coy, in that of Teignmouth. 



