244 SCIILOENBACHIA, 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 may be stated as follows : 

 Shell strongly keeled, usually with strong ribs curved forwards 

 on the flanks; body-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 very stout, usually 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, Deluc. T. 103, fig. 5i;<i. 



Family II. TROPITID^E. 



Shell more or less richly ornamented, provided witli radial 

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

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

 cesses. Wrinkled layer and impressions of the mantle attach- 

 ments entirely absent. 



Genus TBOPITES, 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 sculpture from the inner whorls. The lobes are <lis- 



