NODOSARIA. DENTALINA. 127 



the middle division of the Permian, that is, the Kupferschiefer of Germany, and also in the 

 Zechstein proper and Middle Zechstein ; but it does not appear in the Upper section of 

 the formation in that country. In England, on the other hand, it is not found in the 

 Lower or Middle division, but is confined to the Upper Magnesiau Limestones. 



Subgenus DENTALINA, d'Orbigny. 



NAUTILUS, ORTHOCERAS, OKTHOCERA, NODOSAHIA, auctorum. 



DENTALINA, d'Orbigny, Ehrenberg, Beuss, Richter, Geinitz, d'Eichwald, Parker and Janet, 

 Williamson, Karrer, Brady, Stache, Schmid, S/-c. 



Characters. Shell awl-shaped, subcylindrical, tapering, curved ; composed of several 

 chambers in a linear series ; the primordial segment often very small. Septal lines 

 either straight or oblique ; usually constricted, but occasionally unmarked by any 

 depression of the surface. Aperture terminal, often pouting and nearly always 

 excentric. 



The fact that Dentalina is inseparable except by purely artificial distinctions from 

 Vaginulina and Marginulina scarcely affects the relations of the Carboniferous and 

 Permian forms ; that it only differs from Nodosaria as a straight line of chambers differs 

 from one that is more or less curved, a character of the most trivial significance, is more 

 noteworthy, inasmuch as the common representatives of the type in the Permian 

 Limestones are two forms which differ in no respect except in the direction of the axis 

 and the consequent greater or less obliquity of the septa. The retention of even two 

 names (Nodosaria radicula and Dentalina communis) out of the many that have been 

 given to the smooth Permian Nodosarinee, whilst it is a step towards the simplification 

 of a needlessly confused and complicated nomenclature, is after all a compromise only 

 justifiable on the ground of convenience. 



DENTALINA COMMUNIS, d'Orbigny. PI. X, figs. 17, 18. 



NODOSARIA DENTALINA, Lamarck, 1822. Anim. a. Vert., vol. vii, p. 596, No. 2. 



(DENTALINA) COMMUNIS, d'Orbigny, 1826. Ann. des Sci. Nat., vol. vii, 



p. 254, No. 35 ; Soldani, Testae., vol. ii, pi. cv, fig. O. 

 ( ) d'Orbigny, 1840. Mem. Soc.Geol. France, vol. iv, 



p. 13, pi. i, fig. 4. 



DEKTALIKA PERM IAN A, Jones, 1850. In King's Monogr. Perm. Fossils, p. 17, pi. ivi, 



fig. 1. 



