410 REPORT ON THE STATE CABINET. 



outer chamber so extended and gradually expanding, that it presents an 

 aspect more like Cyktoceras. 



Formation and Locality. — In limestone of the age of the Niagara group, 

 at Waukesha, Wisconsin. 



GENUS ONCOCERAS, Hall. 

 Oncoceras orcas. Hall. 



PLATE XVII, FIGS. 1, 2. 



Cijrtoceras orcas, Hall. Report Progress Geol. Survey of Wisconsin for 1860, p. 42. 18G1. 



This species should properly be referred to the Genus Oncoceras, of 

 which it is the only representative at present known to me in this forma- 

 tion in Wisconsin. 



GENUS GOMPHOCERAS, Sowerby. 



GOMPHOCERAS SEPTORIS, N. S. 



The outer chamber of a Gomphoceras, including the first septum, 

 shows a submarginal siphuncle, with broad sub-elliptical section. The 

 lateral aperture extends to a point nearly have way from the apex to 

 the first septum, and is continued in a narrow constriction nearly to the 

 j,^^, g apex, where it is united with the larger fis. 7. 



aperture : the margin of this is con- 

 tracted into tubular folds, so narrow as 

 to present the appearance of three 

 small rounded lateral apertures, with 

 a similar one on the dorsal side. 

 This peculiarity of the aperture is sufficient for specific determination, 

 when compared with any species known to me. 



Fig. 6 is a lateral view of the outer chamber, and fig. 7 represents the 

 form of the aperture. 



Formation and Locality.- — In limestone of the Niagara group, at Wau- 

 watosa, Wisconsin. Dr. H. Day. 



Gomphoceras scrinium, n. s. 



plate XVIII, FIGS. 1, 2, 3. 



Gomphoceras marct/«, Winchell & Marct; in Memoirs Boston Society Nat. Hist., Vol.1, p. 100, 

 Plate iii, flg. 8. 



A specimen consisting of the outer chamber and first septum, is of 

 moderate size, transversely subcircular, with a very slight angularity on 



