30 DEVONIAN FAUNA. 



Localities. — In the Barnstaple Athenaeum are four specimens from Kingdon's, 

 Shirwell, a doubtful specimen from Top Orchard, and two more without localities; 

 in the Museum of Practical Geology are two poor specimens from Marwood, one 

 from Baggy, and one from West Angle Bay, Pembrokeshire ; in the British 

 Museum is one from Kingdon's, Shirwell ; and in the Woodwardian three from 

 Barnstaple. 



Remarks. — It appears to me that the Shirwell specimens undoubtedly belong 

 to this species. Their surface is smooth ; their section slightly oval (10 : 8) ; the 

 siphuncle central and rather large ; the ratio of the height of the chambers to 

 their width 2 : 5 or 2 : 6 ; the rate of tapering about 1 in 8. The specimen from 

 that locality in the British Museum is a body-chamber which is 110 mm. long and 

 36 mm. wide, and appears sub-cylindrical with a rate of tapering of only 1 in 12. 



In the specimen from West Angle the shell-structure is rather thick, and the 

 surface though smooth to the naked eye is seen under a strong lens to be covered 

 with multitudinous microscopic impressed lines of which a few are slightly stronger 

 than the rest ; a faint carina is seen on its cast similar to that figured on a specimen 

 from Lummaton.^ 



F. A. Bomer's^ version of Orthoceratites regularis, Schlotheim,^ seems to be very 

 similar to this species, but that form has much loftier chambers. 



0. lineare, Miinster, appears to differ in having fine elevated transverse threads 

 instead of simple lineations which do not alter the level of the surface. 



3. Orthoceeas Bakitmense, n. sp. Plate IV, figs. 7, 7 a, 8, 8 a, 8 h. 



Description. — Shell generally small, vertically straight, elongate, conical, 

 probably tapering at about the rate of 1 in 10, covered by elevated, broad, slightly 

 oblique, arching, convex, undefined rings at the rate (in the wider part) of four 

 rings in a height equal to their width, which are separated by shallow concave 

 constrictions about twice as wide as the rings. Septa gently convex, slightly 

 oblique. Section circular or sub-circular with diameters as 9 : 10. Siphuncle 

 rather large, very nearly central. Chambers broad, being apparently about one 

 half their width in height in the smaller part (and probably decreasing to one 

 quarter their width in height when nearer the body chamber). Surface of the shell 

 entirely covered by minute, sharp, crowded, regular, distant, elevated, transverse 

 threads or striae, which sometimes slightly undulate, and are at the rate of nine 

 strige to 1 mm. 



^ Vol. i, pi. XV, fig. 9. 



2 1843, r. A. Eomer, ' Verst. Harzgeb.,' p. 35, pi. x, figs. 4, 5, 8, 



3 1820, Schlotheim, ' Petrefact.,' p. 24. 



