CLASSIFICATION. 15 



Subtribe — Harpocekatin^:, to contain generic groups Arietidse, Amaltheoidas, Ham- 



matoceratidge, 1 Lissoceratidse. 

 Generic group — Hammatoceratidje, to contain generic subgroups Hildoceratinee, 



Hammatoceratinse, &c. 

 The generic subgroup Hildoceratinoa would include such genera as Lioceras, 

 Ludwigia, &c, whilst Hammatoceratinae would include Hammatoceras, Sonninia, 

 &c, but I propose not to give the definition of the subgeneric divisions of the 

 Hamraatoceratidaa at present, as new forms are constantly cropping up and new 

 characters discovered so that it is at present difficult to say what should be 

 included in them. 



1 Hyatt's names Phymatoida?, Hildoceratidse, would only express probably what is equal to the 

 subgroups Hildoceratina?, Hammatoceratina?, and cannot therefore be used here. This name (Ham- 

 matoceratidse) is not open to that objection, but at the same time expresses the same asWaagen's genus 

 Harpoceras. 



