264 CRIOOERAS. 



Genus STOLICZKAIA, Neumayr. 



Forms allied to Hopiites duteiivpleanuii^ with expanded body- 

 chamber, embracing three-fourths ? of a whorl. Margins of 

 aperture curved, produced at the middle of the flanks, slightly 

 emarginate at the external side. Inner whorls with radial ribs 

 which are not interrupted on the external side, and usually here 

 attain their maximum strength ; body-chamber smooth or with 

 thickened ribs ; external side without keel or furrow. Lobular 

 line branched, consisting of a siphonal, two lateral, and one or 

 more less dependent sutural lobes. 



Eight species ; India. 



Stoliczkaia dispar, Stol. T. 112, figs. 6(i4, 665. 



Genus CEIOCERAS, Leveille. 



A part of the evolute cretaceous Ammonites is connected with 

 Lytoceras, another with Olcostephanus ; for a third group, which 

 we will here embrace under the name of Crioceras, the direct con- 

 nection with Acanthoceras and especially with Ac. angulicosta- 

 tum, is shown by the investigations of Pictet and Quenstedt ; it 

 is these evolutes rolled up in one plane, in which, beside the 

 siphonal and the one-pointed antisiphonal lobe, there are on 

 either side two asymmetrically divided laterals and auxiliaries 

 present. Here also, according to the different curvature, several 

 genera have been established, upon the small value of which 

 Quenstedt has expressed himself, and in fact the greatest eapri- 

 ciousness reigns in referring species to one or another of them ; 

 Pictet had already referred all the forms belonging here, which 

 to his time had been embraced under Crioceras or Ancyloceras^ 

 and Toxoceras also, cannot be separated from it ; for the whole 

 group of forms, the oldest name, Crioceras., must be retained. 



Ammonites diverging from Acanthoceras, rolled up in one 

 plane, the whorls of which are not or only partially in contact. 

 Besides the siphonal and the one-pointed antisiphonal lobe, 

 there are, on either side, but two lateral lobes, asymmetrically 

 divided into paired halves. 



Sixtj^-two species. 



Crioceras cristatum, d'Orb. T. lOU, fig. 522. 



