A coNTKiin iiox lo I'liF. c;enis iisn.ixA. 27 



structurally lower tyjie, retnine<l for ages its characters rigid and 

 unsliifting, the times and circumstances produced highly structur- 

 al types, but hartlly inHuenced the survival ot" the ancestral 

 forms. 



The derivation of Xcoschicagerina either from DolioUna or 

 diicctly from iSchicayevhia is a point still undetermined ; how- 

 ever, it is almost certain Avlien tracing the development of 

 Xcoschuayerina craticulifera from the initial chamber onward, 

 that the first numerous chambers are already with transverse 

 septa though not with auxiliary ones. Therefore it is not im- 

 possible that Neoschwagerina is but an imj^roved form of Dolio- 

 Una, unless the basal skeletons are transverse septa much 

 shortened by degeneration, contrary to my present belief. 



The subgenus DolioUna is Schwagerina, only one step 

 higher in structure, and their relationship is so close that the 

 form known as S. Verheeki may likewise be called D. Yerbeehi. 



Triticites secalicus and some other forms, included in /Sch- 

 wagerina by Kkoïow and Schellwiex, undoubtedly show vestiges 

 of a common ancestral group from which the typical FusuUna 

 and Schwagerina sprang. The prototype, we have many good 

 reasons to believe, might have been an elongate form, either 

 fusiform or cylindrical, composed of some number of closely 

 coiled volutions and divided into chambers more or less com- 

 pletely formed by numerous streched septa. Therefore if many 

 of the lower Carboniferous forms of FusuUna could be found 

 and their structural details made known, the mutual relations 

 between Schwagerina and FusuUna s.s. would be cleared up. 



