242 SAGECEllAS, AMALTHEUS. 



the body-chamber. Impressions of the mantle attachment punc- 

 tate or striate. Wrinkled layer consisting of broken up striae. 

 The sutural line of the septa is distinguished by the presence of 

 external adA^entitious lobes. Three groups of lobes may accord- 

 ingly be distinguished : 1. The adventitious lobes. 2. The three 

 principal lobes. 3. The auxiliary lobes. The adventitious and 

 auxiliary lobes always present a similar structure, wliilst the 

 principal lobes frequently present a peculiar form. 



Pinacoceras clearly possesses amongst the Gonialitea an an- 

 cestor in Gon. mulHlobatus, Beyr. 



Twelve species from the Triassic. 

 P. Metternicuii, Hauer. T. 103, tig. 564. 



Genus SAGECERAS, Mojs. 



Is close to Pinacoceras in the form of the sliell and length of 

 the body-chamber, and differs from it in the stru(^ture of the 

 wrinkled layer, the form of the lobes and the direction of the 

 lines of growth in the concave portion. The wrinkled layer is 

 coarsely granular, as in Nautilus, and does not consist of long 

 strige and threads, as in the remaining Arcestida?. The saddles 

 are slender, narrow, tongue-like, entire, the lobes symmetrically 

 divided, simply or doubly, by simple conical teeth. Three 

 groups of lobes, as in Pinacoceras. The lines of growth do not 

 trend backwards, as in Pinacoceras, but forwards. 



Sageceras is already fully developed in the Permian forma- 

 tions, though in these older forms the siphonal process charac- 

 teristic of the ammonite stage is wanting. 



Seven examples from Permian and Triassic. 

 Sageceeas Haidingeri, Hauer. T. 110. figs. 651, 652. 



Genus AMALTHEUS, Montt. 



Siphonal side of the shell sharpened or carinate ; ribs when 

 present, absent at this part or broken ud into tubercles or folds ; 

 the geologically older forms with spiral striifi on the external 

 layer of the shell, which corresponds to the wrinkled layer of 

 the Arcestidae. Body-chamber short, one-half to two-thirds of a 

 whorl long; margin of aperture simply emarginate, with long, 

 external processes, ending in spoon-shaped extremities, some- 



