208 Knowlton — Problematic Organism from the Devonian. 



cavity, with infiltrated translucent calcic carbonate." The per- 

 ipheral marking, as stated above, varies greatly, some being 

 perfectly smooth, others provided with long irregular projec- 

 tions or spines. None seem to be distinctly spiral. 



Professor Williamson examined at the same time examples 

 from Kelley's Island of the Saccammina of Dawson. Of these 

 he says : " Like the Welsh specimens, they have been more 

 opaque than the surrounding matrix, when viewed by trans- 

 mitted light. * * * Each organism has been a hollow sphere. 

 The sphere wall has been much thicker in proportion to its en- 

 tire diameter than is the case among the Welsh specimens. 

 Externally the transverse section of each sphere presents an 

 undulating outline, due to the intersection of prominences and 

 ridges that characterize its surface. Sometimes these projec- 

 tions surround the entire section, but more frequently they are 

 absent from limited portions of the periphery. Occasionally 

 these ridges may be seen pursuing an oblique direction like the 

 bands across the nucleus of a Chara. The central cavity is 

 always occupied by crystalline infiltrated carbonate of lime. 

 Though the sphere wall often exhibits a granular texture, I 

 discovered a radiating structure in a sufficient number of the 

 specimens to convince me that in this respect they have closely 

 resembled some of the Welsh specimens." In conclusion he 

 says : " Whilst I am thoroughly satisfied that these objects are 

 not .Radiolarians, it is not easy to say what they are." 



In order that these organisms may be distinguished they 

 have been referred by Professor Williamson to a provisional 

 genus Calcisphcera, created for the purpose. The Kelley's 

 Island form is called Calcisphwra robusta. 



The Calcisphsera of Williamson has still later been found by 

 Wethered in the Carboniferous Limestone of Gloucestershire.* 

 After discussing the views held by Professor Judd and Pro- 

 fessor Williamson he concludes that "the tests were originally 

 calcareous and not siliceous." " This was urged as a strong 

 argument against regarding the organisms as Radiolaria, and 

 the author, while considering it unwise to come to a decided 

 opinion, believed it safe to say that they are Protozoa." 



The evidence in regard to the nature of this most puzzling 

 organism has been passed in review. It will be observed that 

 the first impression of almost all who have examined it has 

 been that it is a " fruit " of Chara. The principal objection to 

 this view is that the sporostegium has nine or ten cells, while all 

 the heretofore discovered species, both living and fossil, pos- 

 sess only five cells. There is also the difference in the direc- 

 tion of the spiral. The further objection that the organisms 

 are too uniformly distributed throughout the matrix to be 

 * Quart. Joura. Geol. Soc, vol. xliv, p. 91, Lond. 1888. 



