10 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



which the estimated length, including a portion of the apical end, which is broken 

 off, amounts to 385 mm. Septa oblique, 8 mm. apart where the shell has a 

 diameter of about 38 mm., 6 mm. where the diameter is 25 mm. Siphuucle 

 cylindrical, rather wide, central or nearly so. Test perfectly smooth. 



Size. — The length of a compressed example which is only preserved up to the 

 base of the body-chamber, and of which the apex is wanting, amounts to 270 mm.; 

 the diameter at the anterior end being 35 mm., at the apical end 13 mm. The 

 body-chamber of another example has anteriorly a diameter of 43 mm., posteriorly 

 one of 36 mm. (PL IV, fig. 1 c). 



Affinities. — The greater distance of the septa from each other, the slower rate 

 of tapering, and the cylindrical siphuncle separate this species from Orthoceras 

 mhdavatuvi. From Orthoceras mxiUistriatum it is distinguished by its smooth 

 shell, and from Orthoceras acre by its much less slender form and less numerous 

 septa. None of the species described by Phillips, M'Coy, and de Koninck 

 approach the present one nearly enough to make a comparison useful. 



Eemarhs. — Crystallisation within the chambers has caused either total 

 destruction of the septa and siphuncle, or their distortion and shifting out of 

 position in a greater or less degree. The section, PI. IV, fig. 1 d, exhibits them 

 with the least amount of displacement. 



Mr. James Porter, formerly of Queen's College, Cork, after whom this species 

 is named, gave me much assistance in the Cork district, and I have great pleasure 

 in here thanking him for his kind ofiices. 



Localiti/. — Little Island, near Cork. 



Orthoceras vknabcjlum, A. E. Foord. Plate IV, figs. 3 a — d. 



1896. Orthoceuas VENABUi.UM, ^. S. Foord. Ueberdie Orthoceren des Kolilen- 



kalks (Carboniferous Limestone) von Irland. 

 . . . Inaugural-Dissertation zur Erlanguug 

 der Doktorwiirde . . . der Kgl. bayer. 

 Ludwig-Maximiliaus-Uuiversitiit zu Miincben, 

 p. 22. 



Vescrqdion. — Shell rather long, straight, tapering at the rate of 1 : 8. Section 

 elliptic, owing perhaps partly or even entirely to pressure in the rock. Body- 

 chamber long, somewhat less than one-third of the whole length of the shell. 

 Septa shghtly oblique, somewhat approximate in the greater part of the shell, but 

 wider apart towards the body-chamber ; here, whei-e the shell has a diameter of 

 50 mm., they are 20 mm. distant from one another. The septal necks are very 



