ORTHOCERAS PULCHERRTMUM. 19 



Orthoceras hibernicum, A. H. Foord. Plate VI, fio-s. 1 a — e. 



O" 



1896. Orthoceras hibernicum, A. H. Foord. Ueber die Oithoceren des 



Kohlenkalks (Carboniferous Limestone) 

 von Irland. . . . Inaugural-Disserta- 

 tion zur Erlangung der Doktorwiirde 

 . der Kgl. bayer. Ludwig-Maximi- 

 lians-Universitat zu Miinehen, p. 28. 



Description. — Shell slightly curved in the younger part of it; compressed, 

 making the transverse section elliptic, the ratio of the two diameters being as 7 : 5. 

 Rate of tapering about 1 : 4. Only a fragment of the body-chamber is preserved, 

 so that its form and size cannot be determined. The septa are remarkably nume- 

 rous, the last two being only 5*5 mm. apart, while in the earlier part of the shell 

 they are about 7 mm. distant, thus conforming to the usual habit of Cephalopod 

 shells in approaching nearer in the vicinity of the body-chamber. Siphuncle 

 rather large, excentric, about its own width from the centre of the septa ; lying 

 on the concave side of the curvature of the shell ; considerably inflated between 

 the septa. Test very thin ; the surface-ornaments consist of numerous fine, 

 longitudinal, parallel, nearly equal, straight, raised but flattened strias, about three 

 of which occupy the space of 1 mm. ; they are therefore visible to the naked eye. 



Affinities. — In the closeness of its septa and in its ornamentation this species 

 resembles Orthoceras pulcherrimum, but it is easily distinguished from the latter by 

 its much higher rate of tapering, by its rather finer ornamentation, and the 

 excentric position of the siphuncle. From Orthoceras (Actinoceras) striatum, 

 J. Sowerby, it differs by its more rapid rate of increase, much closer septation, 

 and finer ornament. 



Remarks. — Only one example of this fine species has hitherto been found ; there 

 is therefore no material for the study of the variations to which the species may 

 be subject. 



Locality. — Clane, county of Kildare. 



Orthoceras pulcherrimum, A. H. Foord. Plate VI, figs. 2 a — c. 



1896. Orthoceras pulcherrimum, A. H. Foord. Ueber die Orthoceren des 



Kohlenkalks (Carboniferous Limestone) 

 vonlrland. . . . Inaugural-Disserta- 

 tion zur Erlangung der Doktorwiirde 

 . . . der Kgl. bayer. Ludwig-Maxi- 

 milians-Universitiit zu Miinehen, p. 29. 



