GENUS STEPHANOCERAS. 



471 



Family.— AEGOCERATIDtE— continued. 



Genus VII. — Stephanoceras. Waagen, 1869. 



Family — Coronaeii, Von Buck. Abh. konig. Akad. Wissensch. Berlin, Ueber 



Ammoniten, p. 145, 1832. 

 Coronaten, Quenstedt. Cepbalopoden, p. 175, 1849. 



Planulati, Pictet. Traite" de Paleontologie, t. ii, p. 693, 1854. 



Coronati, Seebach. Hannoverscke Jura, p. 147, 1864. 



Genus — Peronoceras (pars), Hyatt. B'oss. Cephalopods ; Bulletin of tbe Museum of Com- 

 parative Zoology, Harvard's College, Cambridge, 

 Mass., vol. i, p. 85, 1863—1869. 

 Deroceras (pars), — lb., p. 84. 

 Dacttlioceras (pars), — lb., p. 95. 

 Stephanoceras, Waagen. Formenreihe, Benecke's Beitr., ii, 247, 1869. 



— W. Neumayr. Zeit. Deutscb. Geol. Gesellschaft, Bd. lxxvii, 



p. 915, 1875. 



The general form of the shell in the genus Stephanoceras is very variable ; the siphonal 

 area is in general large and round without keel, border, or channels, and the sculpture is 

 often highly ornamental. From the umbilical suture rises a short stout rib which often ends 

 in a tubercle at the middle or upper part, from which spines project as in Steph. Deslong- 

 champsii (fig. 202) ; from the tubercle two or three smaller costse pass over the area and unite 

 with their fellows from the opposite side. Sometimes the tubercles are absent, and a number 

 of fine encircling costae complete the sculpture, as seen in Stephanoceras commune and 



Fig. 196.— Stephanoceras commune. Fig. 197 .—Stephanoceras annulatum. Fig. 198. — Stephanoceras BraiJcenridgii. 



in Stephanoceras annulatum in which the style of costation just described is very well 

 shown. 



