128 CARBONIFEROUS AMMONOIDS OF AMERICA. 



viuced tliat it is merely the young- of some member of the Glyphiocera- 

 tidfe, probably either GonioJoboceras or Dimorphoceras. At any rate, the 

 occurrence of the Primordialidfe in the Upper Coal Measures is extremely 

 unlikely, since that family is not known above the Devonian. 

 Occurrence. — Upper Coal Measures, Kansas City, Mo. 



Siaperfamily ^RCESTID^ai:. • 



The ontogeny of but few of the Paleozoic forms assigned to the Arces- 

 tidse has been investigated, but Triassic species show in their adolescent 

 stages strong resemblances to some of these, and enable us to piece out their 

 history. 



The genera thought to represent the Arcestida^ in the American Carbon- 

 iferous are AfjatJiiceras, Popanoceras, ShumardUes, and Waagenoceras. Haug" 

 has placed the first with the Glyphioceratidfe, and the second with the 

 Agoniatitida', leaving only Waagenoceras as an undoubted representative of 

 the Arcestidai. Tliis classification, however, is based purely on resemblances 

 of adults, hence the writer has preferred to follow Karpinsky, whose classi- 

 fication seems to agree more closely with the facts brought out by the 

 writer's investigation of the ontogeny of ShumardUes, Arcestes, and Parapo- 

 panoceras Also the supposed species of Agathiccras, on which Haug's opinion 

 was based, is shown in the present paper to be a Schistoceras, and to belong- 

 to the Glyphioceratida?. Hyatt" classed Popanoceras under the Prolecanitidse, 

 with which group, as now understood, it has manifestly no kinship. In his 

 most recent work Hyatt' classed Popanoceras in the family PopauoceratidfB 

 along with Waagenoceras under the superfamily Arcestida. 



In the Paleozoic Arcestida? may be found at least two families with 

 characteristics in common that point to a common origin in the gastrioceran 

 •branch of the Glvphioceratida?, but with sufficient differences to make prob- 

 able their derivation from different genera. Agathiceras, Adrianites, Popan- 

 oceras, Stacheoceras, and possibly Doryceras and Clinolohus all seem to be 

 nearly related, and form a transition from the goniatitic Paralegoceras, 

 through Agathiceras, into genuine ammonites characterized by a ti'i;i?nidian 

 development of the lobes. Hyatt has classed some of these genera under 

 the group Popanoceratida, which term is here used for this branch of the 

 Arcestes-Vike forms. 



«Etudes sur les Goniatites. *Proc. Boston Soc. Nat. Hist., Vol. XXII, p. 337. '' Cephalopoda, p. 564. 



