﻿232 BEITISH FOSSIL CEPHALOPODA. 



Suborder AMMONITOIDEA. 



Genus G-oxiatites. 

 Goniatites (?) nautilaceum, Sowerby, PI. XXYIL fig. 4. 



1838. Phragmoceras (?) nautilaceum, Sowerby in Murchison's 'Sil. Syst.,' pi. 10, fig. 2 (not fig. 3), p. 622. 



Type. — This only shows the surface flattened on a piece of mudstone. Its shape 

 is so peculiar that Sowerby placed a query after the genus, but he associated with it 

 a really different form without that peculiarity. It has, as he states, very much 

 the aspect of a Nautilus, that is of a Nautilus of Neozoic age, inasmuch as it is nearly 

 involute, the last whorl occupying T 7 T of the whole diameter, and the umbilicus being 

 nearly zero. The ornaments are slightly irregular, transverse diverging ribs, im- 

 bricating slightly backwards, and very feeble striae parallel to them. These are 

 convex towards the aperture, curving first forward and then back towards the out- 

 side, about 24 in half a whorl. The aperture shows no signs of contraction, but the 

 curvature remains normal. No septal characters are visible. The absence of any 

 characters of septa, siphuncle, and aperture must necessarily leave the genus doubt- 

 ful till better specimens are met with. In the meantime there is no contraction of 

 the body-chamber, and the shape is not that of a Phragmoceras. The shape, indeed, 

 being all we have to go by, points to Goniatites as the most probable genus, 

 examples of which from Silurian rocks have a similar shape, and we can say 

 this of no other genus. Diameter, 2£ inches. In the Museum of the Geological 

 Society. From the Lower Ludlow. 



General Description. — The type is unique. 



Distribution. — In the Lower Ludlow at Charlton Brook, south end of the 

 Longmynd. 



Phillips records some species by this name from Freshwater, Haverfordwest, and 

 Llandeilo, and Salter from the Upper Llandovery, Plas Madoc, but there is every 

 probability they mean some other form. 



