GENUS STEPHANOCERAS. 



471 



Family.— k'E.GOC^^kimm— continued. 



Genus VII. — Stephanoceras. Waagen, 1869. 



Family — Coronaeii, 



coronaten, 

 Planulati, 



CoEONATi, Seebach 



Genus — Peronoceras (pars), Hyatt. 



Deeoceras (pars), — 

 Dacttlioceeas (pars), — 

 Stephanoceras, 



Von Buck. Abh. konig. Akad. Wissensch. Berlin, Ueber 



Ammoniten, p. 145, 1832. 

 Quenstedt. Cepbalopoden, p. 175, 1849. 

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

 Hannoversche Jura, p. 147, 1864. 

 Foss. Cephalopods ; Bulletin of the Museum of Com- 

 parative Zoology, Harvard's College, Cambridge, 

 Mass., vol. i, p. 85, 1863—1869. 

 lb., p. 84. 

 lb., p. 95. 

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

 W. Neumayr. Zeit. Deutsch. Geol. Gesellschaft, Bd. Ixxvii, 

 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. Beslong- 

 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 costse complete the sculpture, as seen in Stephanoceras commune and 



S 



Fia. Vi^.—Steiyhnno 



ommune. Fio. 197. — Stephanoceras annulatam. FiG. 198. — Stephanoceras Sraikenridgii. 



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

 shown. 



