APPENDIX 3' 5 



E. Receptaculites and Arch^ocyatiius. 

 In "The Dawn of Life" (1875). reference was 

 made to the singular and complicated organisms of 

 the Upper Cambrian and Ordovician systems known 

 as Receptaculites, which at that time was generally 

 re-arded as foraminiferal. and is still placed b)' 

 Ziuel, in his great work on Paleontology, among 

 forms' doubtfully referable to that group. It has 

 also been referred to Sponges, though on ver)' 

 uncertain grounds. It has not, however, so far as 1 

 am informed, been traced any farther back than the 

 Upper Cambrian (Calciferous), and no structural 

 links are known to connect it with either Eozoon or 

 Archa^ozoon. For this reason it was omitted m the 

 text • but I think it well to mention it here, a.id 

 to direct attention to it as possibly one of the 

 complex Protozoa which may be traced far back 

 toward the beginnings of life.' 



Another primitive and generalized genus men- 

 tioned in the text is Arclu.ocyathus of K.lhngs, 

 .-hose headquarters seem to be in the Lower Cam- 

 brian, and wh>ch may probably be traced farther 



back. . 



1 Billings, " Palreozoic Times." 



