Lower Palceozoic Rocks of the South of Scotland. 47 



single species. The preservation of the Radiolaria in this 

 Ordovician chert, which has evidently been subjected to con- 

 siderable disturbance, is an indication that if these organisms 

 had entered largely into the composition of other beds of chert 

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

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

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

 and other siliceous rocks may be attributed to Radiolaria ; 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 Radiolaria. 



Description of Species. 



In attempting to classify these ancient Radiolaria I have 

 followed as far as possible tlie latest system of Prof. Heeckel, 

 contained in the ' Challenger ' Report 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 compreliension 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 genera to include some of them. 



Class RADIOLARIA, xMiiUer. 



Subclass SPUMELLARIA, Ehrenberg. 



Order SPH^RELLARIA, H^ckei. 



Suborder Sph^roidea, Hgeckel. 



Family Liosphaerida, H^eckel. 



Sphffiroidea without radial spines on the surface of the 

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

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



Genus Styptosph^ra, Ha3ckeL 



Liosphserida 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. naturliist. Gesellsch. zu Hannover^ 1883-87 (1888), p. 6Q. 



