14 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



chamber unknown. Septa somewhat oblique, deeply concave, somewhat widely 

 separated from one another — that is, 8 mm. apart where the diameter of the shell 

 amounts to 30 mm., 3*5 mm. from each other towards the apical extremity, where 

 the shell measures 15 mm. in diameter. The distance between these two measure- 

 ments is 75 mm. Test quite smooth. 



Affinities. — This species differs from Orthoceras Hindei and from 0. subclavatum 

 by the horizontality of its septa, and it is also distinguished from the former by 

 its smaller siphuncle. Its septa are much wider apart than those of 0. subclavatum. 

 These differences seemed to justify the distinctness of the present species, of 

 which only one has up to the present time been recognised. 



Locality. — Little Island, near Cork. 



II. Group Annul ata. 

 Orthoceras l^vigatum, F. M'Coy. Plate V, figs. 1 a — e. 



1843. Oethocebas annulatum, L. G. de Koninck. Precis eletu. de Geologie, 



par J. J. d'Omalius, p. 515. (Not of Sowerby.) 

 1S42-4. — dactyliophoeum, L. G. de Koninck. Descrip. Anim. Foss. 



Belgique, p. 318, pi. xlvii, fig. 2; pi. 

 xlviii, figs, la, b. 



1844. Cycloceeas l^evigatum, F. M'Coy. Synopsis of the Char, of the Carb. 



Limest. Foss. of Ireland, p. 10, pi. i, fig. 3. 



1850. Oethocebas dactyliophoeum, A. d'Orbigny. Prodr. de paleont. stratigr., 



vol. i, p. 113. 



1851. — — C. G. Giebel. Fauna der Vorwelt, Bd. iii, 



Abth. 1, p. 255. 

 1860. Cycloceeas l^evigatum, B. Griffith. Journ. of the Geol. Soc. of Dublin, 



vol. ix, p. 55. 

 18S0. Oethocebas l^evigatum, L. G. de Koninck. Faune Calc. Carb. Belgique 



(Ann. Mus. Boy. d'Hist. Nat. Belgique, ser. 

 Paleont., vol. v), pt. 2, p. 70, pi. xli, fig. 4. 

 ? 1880. Cyetoceeas dactyliophoeum, L. G. de Koninck. Ibid., p. 30, pi. sxxiv, 



fig. 1. 

 1896. Oethocebas l.evigatum, A. H. Foord. Ueber die Orthoceren des Kohlen- 



kalks (Carboniferous Limestone) von Irland. 

 . . . Inaugural-Dissertation zurErlangung 

 der Doktorwurde . . . der Kgl. bayer. 

 Ludwig-Maximilians-Universitat zu Munchen, 

 p. 25. 



Description. — Shell straight, or slightly curved in the apical region; tapering 

 very slowly, viz. at the rate of 1 : 26. Section circular. Body-chamber 



