AMMONITID^. 19 



appear in the upper Jura of Stramberg, where a considerable 

 number of clifl'erent forms are found. 



The genus fficotraustes was created for species of the group 

 of 0. genicnlaris,Waagen; Neumayria for such species as 0. 

 trachynotus and 0. Hauffiana, of Oppel. 



Haploceras, Zittell, 1810. 



Syn. — Lissoceras and Puzosia, Bajde, 1818. 



Distr. — 16 sp. Jurassic, Cretaceous. H. ligatum^ d'Orb. 

 (xxxiv, 49, 50). 



Estaljlished for a group allied to Oppelia from the middle and 

 upper Jurassic, which is characterized by very feeble or no sculp- 

 ture ; also some cretaceous forms, as Hapl. Grusanum^2iVQ. placed 

 here ; and with them forms very pronounced wedge- or chisel- 

 shaped in section, as Hapl. belus ; finally, species with quite sharp 

 external sides, as Hapl. nisus, Orb. 



In other Jurassic species of Haploceras, there is gradually 

 developed a transverse sculpture, which is confined to the external 

 side of the body-chamber (Hapl. jungens^ Neum., carachtheis, 

 Zeuschner). 



In certain upper Jurassic forms, which are allied to Hapl. 

 carachtheis, the sculpture graduallj'^ passes from the external side 

 over to the flanks in feebly undulating ribs, as is shown in Hapl. 

 cristiferum, Zitt. ; better developed in Hapl. wohlerij 0pp. ; and 

 this feature is repeated in Hapl. difficile, Orb., Gleon, Orb., 

 bicurvatum, Leym. 



Finally, species of Haploceras appear which are distributed 

 in the cretaceous, with constrictions reaching forwards (Hapl. 

 Beudanti, Parraudieri) , a peculiarity which does not occur in 

 anj^ Jurassic form; the inner whorls here serve as sure guides, 

 aside from the agreement of the lobular markings, since the37^ 

 represent a typical Haploceras with entirely smooth whorls. 

 With these furrows a sickle-shaped undulating radial sculpture 

 is gradually combined, and a group of forms results, of which the 

 principal tjq^e is Hapl. planulatum, Sow. 



In spite of this great manifoldness, it is very easy to distin- 

 guish the representatives of Haploceras from strata Avhich are 

 lower than the turonian and downwards, by their whole habitus 

 and lobes, yet nothing is more difficult to express in words. 



This genus corresponds with Ammonites Ligati of d'Orb. 

 Bayle changed the name to Lissoceras, because Haploceras was 

 preoccupied by d'Orbigny ; the latter's species is, however, a 

 sjaionym of Cyrtoceras. 



Stephanocerafae. 



Form very variable. Aptychus calcareous, granular, formed 

 of two plates, which are sometimes joined at the median line. 

 The Stephanoceratse ma}^ be subdivided into normal, with regular 



