269 
eZass-CEPHALOFOBA. 
0;Y^£>r— TETEABRANCHIATA. 
Oeniis — GONIATITESj de Haau. 
Gontatites miceomphaltjs. J. Morris. 
PL XXIV, Pig. 5. 
l^ellcroplion micr omphalus , J. Morris, 1845, in Strzelecki’s Pliys. Descr. N. S. Wales and 
V. D. Land, p. 288, pi. 18, fig. 7. 
55 55 P. McCoy, 1847, Ann. Mag. Nat. Hist., XX, p. 308. 
55 55 J. D. Dana, 1849, Geol. Wilkes’ U. S. Explor. Bxped.,p. 708 
pi. 10, fig. 6. 
55 undulatus, Idem, 1849, ihid., p. 707, pi. 10, fig. 4. 
This shell is cliscoiclal, of moderate size, convex on the sides, with a 
rounded hack. The several whorls of the spire envelope each other almost 
completely, and leave only a small umbilicus. The specimens being deprived of 
their shells, their surface ornamentation can be described approximately only ; 
but as the shell was very thin, as in most Goniatites, the traces on the casts 
show that the surface was covered with indistinct lines of growth, interrupted 
at set distances by transverse depressions, which extend into the dorsal part 
and there produce a large sinus, the convexity of which is turned backwards, 
and indicates the shape of the ujoper margin of the aperture. The aperture 
is rounded in front, and very much hollowed out behind by the whorl of the 
spire, which makes it sub-semilunar. I have discovered no traces of septa 
on these specimens. 
Dimensions. — The diameter is twenty-two millimetres, the thickness 
thirteen, and the height of the aperture six millimetres. 
Delations and Differences. -=-V>oi\\ Professor Morris, who first described 
this species, and Mr. Dana remarked that it had much more the appearance 
of Goniatites than of Dellerophon, but they placed it with the latter on 
account of the complete absence of septa. Por my part, I am convinced 
* [A. H. Foord, Geol. Mag., 1890, VII (3), p. 104; E. Etheridge, Junr., Procs. R. Phys. Soc. Edinb., 
1880, V, p. 304; Geol. and Pal. Q’land., 1892, p. 294; G. (Prolecanites ?) micromphalus, R. Etheridge, Junr., 
Records Geol. Survey N. S. Wales, 1894, IV, p. 36, t. 7, f. 9-14 ; Agathkeras (?) micromplialum, A. H. Foord 
and A. H. Crick, Cat. Foss. Cephal. B. M. Nat. Hist. 1897, HI, p. 271. — W.S.D.] 
