CEPHALOPODA. 
455 
This species has the form, and proportions of G. discoideus and G. uniangularis; 
but is readily distinguished by its open umbilicus, and by the shallow umbilical 
lobe, the high lateral saddle, acute ventro-lateral lobe, and short dorsal lobe. 
It differs from all the other forms known to me, in the disposition and 
character of the septa, and the proportions of the umbilicus. In the latter 
feature, and in its septal arrangement, it is somewhat nearly related to G. lamel- 
losus of Sandberger ( Verstein. des Rheinischen Schichtensystems in Nassau, tab. 8, 
fig. 1), but is a much less rotund form, with the lateral faces more gently curved 
and the periphery narrower.. The species is of rare occurrence, and little is 
known of its vertical and horizontal distribution. 
Formation and locality. In the Chemung group, near Ithaca, N. Y. 
Goniatites complanatus. 
PLATE LXX, FIGS. 8-11. 
Clymenia? complanata, Hall. Geolog-. Surv. of N. Y. : Rep. Fourth Dist., pp. 243, 244, fig. 5. 1S43. 
Clyjnenia complanata, “ Descriptions of New Species of Fossils, etc., p. 35. 1881. 
“ “ “ Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 63. 1862. 
Clymenia Erato, Hall. Descriptions of New Species of Fossils, etc., p. 36. 1861. 
“ “ “ Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 64, .pi. 10, fig. 1. 1862. 
Goniatites complanatus, Hall. Descriptions of .New Species of Goniatiihe, p. 1. May, 1874. 
“ “ “ Twenty-seventh Rep. N. Y. State Mus. Nat. Hist., p. 132. 1875. 
Clymenia Erato, Hall. Illustrations of Devonian Fossils: Cephalopoda, pi. 70, figs. 6, 7. 1876.- 
Goniatites (Clymenia?) complanatus, Hall. Illustrations of Devonian Fossils: Cephalopoda, pi. 70. 1876. 
Shell discoid; inferring from the depth of the umbilicus, the disc may have 
had a thickness of about eight mm., where the diameter has been about 
thirty-five mm. 
Volutions about four or more, gradually expanding from the apex, the 
outer ones embracing the inner for about one-fourth to one-third of their 
width, or sometimes a greater proportion. In their natural condition they 
are rounded and subventricose, but are usually flattened. Umbilicus wide, 
exposing all the inner volutions. Transverse section short, semi-elliptical, or 
trapezoidal, with the apex rounded, and the base indented by the preceding 
volution, the baso-lateral angles auriculate. The enlargement of the volutions 
is very gradual to the termination of the septate portion, where the rate 
of increase is moderately augmented. 
