26 DEVONIAN FAUNA. 



funnels do not approacli near enough to interrupt the sutures or affect the depth 

 of the ventral lobes. But one Carboniferous species is known — 8. evoluta, Phil."^ 

 De Koninck proves this genus to belong to the Nautilidae. 



1. SoBCLYMENiA Symondsii, MS. Plate VII, figs. 3, 3 a, 4. 



Description. — Shell very large, discoid, flattish, of two or three volutions, 

 which appear probably to have been free, and to leave a central vacuity. Whorls 

 rapidly increasing, sub-quadrate, nodose ; ventrally broad, concave ; dorsally 

 narrow, slightly concave. Sides convex, rising slowly from their dorsal side to 

 the shoulder for about two-thirds their height, and then curving down to the 

 ventral side, where they seem bounded by a sharp angle ; barred by distant ridges 



which swell into large lofty bluntly conical nodes, at the shoulder, about twelve 

 nodes to a whorl. Body-chamber probably large. Suture-line with a very long 

 V-shaped central saddle, rather deep and convex central lobes, and low lateral 

 saddles. Ornament consisting of small, crowded, unequal, rounded transverse 

 riblets, divided by narrower grooves, running slightly backward from the inner 

 margin to the shoulder, where they vanish ; crossed by comparatively few distant 

 impressed threads, which are absent on the shoulder but reappear on the ventral 

 part of the side. Shell-structure probably not massive. 



Size of cast. — Diameters 165 mm. and 110 mm. Width 65 mm. 



Locality. — In the Museum of Practical Geology are two specimens from 

 Luscott, near Braunton, one of which is a very large cast retaining in one place 

 signs of the surface-markings, and the other the mould or inner surface of a 

 smaller shell. 



Remarks. — The largest specimen in the Museum is a splendid fossil, but in 

 many respects it is most difficult to interpret. In the first place it has evidently 

 been subjected to very great slant pressure, which has compressed it, altered 

 the character of its coiling, and obscured the true shape of its whorls. Again, its 

 whorls are so widely separated that it is difficult to imagine that they were in 

 contact unless the shell-structure were immensely thick, which the fact of the 

 cast bearing traces of the surface-ornament renders very improbable. Moreover^ 



1 1884, Hyatt, ' Proc. Boston Soc. N. H.,' vol. xxii, p. 293. 



