244 SCHLOENBACHIA, TROPITES. 



Sixty-eight species enumerated ; Triassic, Jurassic and Cre- 

 taceous. 

 Amaltheus margaritatus, d'Orb. T. 109, figs. 635, 636. 



Genus SCHLOENBACHIA, Neumayr. 



This genus embraces the very natural group of Cristati ; to 

 these I add the Schl. Germari^ Reuss., whose affinity to these is 

 indicated besides other striking characters, by a toothed keel. 



The characters of Schloenbachia ma}^ be stated as follows : 

 Shell strongly keeled, nsuall}' with strong ribs curved forwards 

 on the flanks ; bod^^-chamber two-thirds of a whorl long, drawn 

 out at the sickle-shaped aperture into a long, beak-like process, 

 which is either prolonged in conformity with the curvature of 

 the spiral or bent outwards. Siphon ver}^ stout, usuall}' lying 

 in the keel, which is often cut off from the lumen of the shell by 

 a calcareous septum. Lobes not much branched, with bodies 

 which are narrower than the saddles ; only one distinct auxiliary 

 lobe ; which is wanting in some forms. Siphonal lobe usually as 

 long or longer than the first lateral. In some species a great 

 reduction in the number of branches of the lobes takes place, 

 so that they approach a Ceratitic form. (Schl. senequeri and 

 halophylla.) 



Forty-six species. 



SCHLOENBACHIA CRISTATA, DcluC. T. 103, fig. 560. 



Family II. TROPITID^. 



Shell more or less richly ornamented, provided with radial 

 ribs, which almost always support on the edge of the convex 

 portion (frequently also on the sides) knobs and spinous pro- 

 cesses. Wrinkled layer and impressions of the mantle attach- 

 ments entirely absent. 



Genus TROPITES, Mojs. 



Body-chamber long, embracing one and three-quarters to one 

 and one-half whorls. The strong sculpture is interrupted on the 

 convex portion of the shell ; frequently a median keel is present 

 on the same. At the aperture the convex portion is prolonged 

 into a broad, short lobe. The last whorl frequently differs in 

 form and sculptui'e from the inner whorls. The lobes are dis- 



