Lower Paheozoic Rocks of the South of Scotland. 47 



single species. Tlic preservation of the lladiolaria in tliis 

 Ordovician chert, whicli has evidently been subjected to con- 

 siderable disturbance, is an indication that if these organisms 

 had entered largely into tiie composition of other beds of chert 

 in this country they wduld probably ere now have been recog- 

 nized in them. The observations of Dr. liiist * have led him 

 to conclude that on the continent in the majority of cases chert 

 and other siliceous rocks may be attributed to lladiolaria ; but 

 in this country, according to present experience, similar rocks 

 are mainly derived from the remains of siliceous sponges and 

 very exceptionally from those of lladiolaria. 



Descri'piiun of Species, 



In attem{)ting to classify these ancient lladiolaria I have 

 followed as far as possible the latest system of Prof. Ha;ckel, 

 contained in the ' Challenger ' lleport on this group. In this 

 elaborate work the limits assigned to genera are extremely 

 narrow and precise, and it is no wonder therefore that even 

 with the greatest desire for comprehension it should be found 

 impracticable to fit all these fossils into the divisions, nume- 

 rous though they are, which have been already established, 

 and I have therefore reluctantly been obliged to propose 

 additional a'enera to include some of them. 



Class RADIO LABIA, MuUer. 



Subclass SPUMELLARIA, Ehrenberg. 



Order SPH^ERELLARIA, H^ckel. 



Suborder S P ll ^ R I D E A, Ha^ckel. 



Family Liosphserida, Ha3ckel. 



Sphffiroidea without radial spines on the surface of the 

 spherical shell ; living solitary (not associated in colonies). 

 (' Challenger ' lleport, part i. p. 59.) 



Genus STYPTOSPHJiRA, Ha3ckeL 



Liosphffirlda forming a solid sphere of spongy framework, 

 without enclosed medullary shell and without central cavity. 

 (Chall. Rep, part i. p. 86.) 



Styptosphcera antiqua, sp. n. (PI. III. fig. 1.) 

 • The irregularly reticulate or spongy framework appears to, 

 * Jahresb. d. naturhist. Gesellsch. zu Hannover, 1883-87 (1888), p. 56. 



