MONOGRAPH 



ON THE 



CARBONIFEROUS CEPHALOPODA OF IRELAND. 



Sub-order NAUTILOIDEA. 



Family Orthoceratid.e. 



A. Loxgicoxes. 



I. Group L.evia. 



Sub-group Gylindriformes (siphuncle cylindrical). 



Genus Orthoceras, Breyn, 1732. 



Orthoceras Leinsterense, A. H. Foord. Plate I, figs. 1 a — c. 



1896. Oethoceras Leixstekense, A. H. Foord. Ueber die Orthoceren des 



Kohlenkalks (Carboniferous Limestone) 

 von Irland. . . . Inaugural-Disserta- 

 tion zurErlangung der Doktorwiirde 

 . der Kgl. bayer. Ludwig-Maximilians- 

 Universitat zu Muncheu, p. 13. 



Description. — Shell somewhat elongate, straight, tapering at the rate of about 

 1:7. Section elliptic, perhaps partly by pressure, the ratio of the greater to 

 the lesser diameter being as 7 : 6. Body-chamber of moderate length, about 

 120 mm., which probably represents not more than one-fourth of the entire 

 length of the shell ; the specimen, however, is not perfect enough towards the apex 

 to supply material for accurate measurement. There is a small, well-marked 

 constriction on the cast of the body-chamber, just below the aperture, but this 



1 



