CEPHALOPODA. 453 



This species, both in its exterior characters and internal arrangement, is 

 quite distinct from any other form known among the collections from the New 

 York formations. In many of its characters it is closely similar to G. retrorsus, 

 von Been. In the manner of its septa it is very similar to the var. lingua and 

 var. typus of that species, as represented by Sandberger, Verstein. des Rhein. 

 Schichtensystems in Nassau, p. 109, tab. 10, fig. 20, and 10 a, figs. 4, 5; while 

 the var. undulatus, pi. 10 a, figs. 17, 19, represents the surface-markings and the 

 revolving carina}. The var. auris, pi. 10, figs. 11-13, is represented in the 

 young of our species. 



Formation and locality. In the arenaceous shales of the Portage group, on the 

 shores of Lake Erie, in Chautauqua county, N. Y. 



GONIATITES SIMULATOR. 



PLAT! s I. XIX, FIGS. 1, 2; LXXIV, FIG. 8. 



Ooniatites simulator, Hall. Descriptions of New Species of Goniatidse, p. 2. May. 1874. 



" " " Twenty-seventh Rep. N. Y. State Mus. Nat. Hist., p. 133. 1875. 



" " " Illustrations of Devonian Fossils : Cephalopoda, i)l. 69, fig's. 1, 2. 1876. 



Shell discoid, lateral faces gently curving from the umbilical side to the margin 

 of the periphery, which is very symmetrically rounded. The transverse and 

 lateral diameters, measured at the first quarter volution of the air-chamber, 

 are about as eighteen to forty-two. 



Volutions, three or more, closely coiled, leaving a moderately wide umbili- 

 cus in which less than hall the width of each volution is exposed ; inner 

 margins of the volutions abruptly, and in the older ones almost rectangularly, 

 curving into the umbilical depression. Transverse section symmetrically 

 semi-elliptical, with the base deeply indented by the inclosed inner volution. 

 The enlargement of the volutions to the first quarter of the outer chamber is 

 regular and somewhat rapid, the last septate volution increasing in its outer 

 half from twelve to seventeen mm. The diameter of the septate portion of 

 the tube, at one volution back of the broken margin of the outer chamber, as 

 compared with the width of the latter, is about as twelve to twenty-three. 



The chamber of habitation is preserved for about one-quarter of a volution, 

 and continues with about the same rate of enlargement as the preceding volu- 



