Lower Pu/ieozoic Rocks of the South of Scotland. 59 



the secondary rays tapering to an acute point. The entire 

 length of one ot" the rays is "37 millim. I liave only seen a 

 single impcrt'ect specimen of this form in the chert from 

 Hartree Hill. 



EXPLANATION OF THE PLATES. 



Plate IIL 



liy. \. Sfifptosphcrra aiitiqua, ?p. n. 



Fi</. 2. f^/)o/ii/(>j)/cyma j>riiicuin, sp. n. Tlie iuuor medullary sphere is 



shuwu by tlu> dark central portion. 

 Fi(/. 3. Dunjiipluera reticuhita, sp. n. The radial spine in this specimen 



has been partially dislocated, and some of the mesh-apertures 



are inlilled with tiie dark staining material. 

 Fiy. 4. Dorifsph(cra tii.vd, sp. n. la this specimen the radial spine is 



viewed obliquely. 

 Fiy. 5. Dory.<ph(er(i nucula, sp. u. 

 Fiy. 0. Stauropleyma barbatum, sp. u. The medullary sphere in this 



specimen is indicated by the partially clear central space. 

 Fiy. 7. Dory diet yum simpler, sp. n. 

 Fiy. 8. Dorypleyma yracile, sp. n. 

 Fiy. 9. Dorypleynta naxufum, sp. n. The lower portion of this specimen 



has been displaced by a quartz-vein. The iimer or medullary 



sphere is indicated by the darker central area. 

 Fiy. 10. Diplopleynta cinctum, sp. n. 

 Fiy. 11. Hdliumina vcfiistiiDt, sp. n. The mesh-apertures in the specimen 



are indistinct, owing to the dark infilling. 



Plate IV. 



Fiy. 1. Acanthosph(pra (oitiqiia, sp. u. The specimen is iiiperfect, a por- 

 tion to the right having been cut oil by a quartz-vein. 



Fiy. 2. Triposphcera hastata, sp. n. In tliis specimen only one of the three 

 radial spines is preserved entire, the bases only of the other two 

 remain. The inner sphere is partially clear and has not been 

 infilled with the opaque material like the outer sphere. 



Fiy. 3. D(jrysphcera reticulata, sp. n. 



Fiy. 4. Stauropleyma diffusum, sp. n. A quartz-vein traverses the right- 

 hand portion of the specimen. 



Fiy. 5. Stauropleyma brevispina, sp. n. The upper portion has been dis- 

 placed by a quartz-vein. 



Fiy. 6. Stauropleyma compressum, sp. n. 



F'ig. 7. Stnurodoras yracilis, sp. n. Only the base of the lower spine 

 remains. A quartz-vein traverses the specimen. 



Fiy. 8. Haliomma cornutum, sp. n. 



Fiy. 9. Tripoq)hcera reachii, sp. n. 



Fiy. 10. Triposphcera densa, sp. u. 



Fiy. 11. Triposphcera armata, sp. n. 



Fiy. 12. Sphccrozouyn patulum, sp. n, A geminate spicule, the rays im- 

 perfect, referred to this species. 



The figures have been drawn by transmitted light from microscopic 

 sections of the chert-rock in which the Radiolaria are imbedded ; they 

 are all enlarged to the same scale of 200 diameters. The specimens are 

 all from the same zone in the Ordoviciun or Lower Silurian strata of the 

 Southern Uplands of Scotland ; the particular localities are given in the 

 text. 



