Lower Pulceozoic Rocks of the South of Scotland. 59 



the secondary rajs tapering to an acute point. The entire 

 length of one of the rajs is '37 millim. I have onlj seen a 

 single imperfect specimen of this form in the chert from 

 Hartree Hill. 



EXPLANATION OF THE PLATES. 



Plate HI. 



Fig. 1. Stj/pfosph(era aiitiqita, sp. u. 



Fiff. 2, Spongoplejma priscum, sp. n. The iuner medullary sphere is 



shown by the dark central portion. 

 Fiff. 3. Dorysphceru reticuluta, sp. n. The radial spine in this specimen 



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



are infilled with the dark staining' material. 

 Fig. 4. Doi-ysphccra laxa, sp. u. In this specimen the radial spine is 



viewed obliquely. 

 Fig. 5. Dorysphceru nuciila, sp. n. 

 Fiy. (3. Stauroplegma barbatimi, sp. n. The medullary sphere in this 



specimen is indicated by the partially clear central space. 

 Fig. 7. Dorydictyum si^nple.v, sp. n. 

 Fig. 8. Dorypleyma gracile, sp. n. 

 Fig. 9. Dorypleyma nasutum, sp. n. The lower portion of this specimen 



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



sphere is indicated by the darker central area. 

 Fig. 10. Dipluplegina cinctmn, sp. u. 

 Fig. 11. Haliommn vetiistum, sp. n. The mesh-apertures in the specimen 



are indistinct, owing to the dark infilling. 



Plate IV. 



Fig. 1. Acanthosphcpra antiqua, sp. n. The specimen isiiLperfect, a por- 

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



Fig. 2. 2'riposphcera hastuta, sp. n. In this specimen only one of tJie three 

 radial spines is preserved entire, tlie 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. 



Fig. 3. Dorysphceru reticulata, sp. n. 



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

 hand portion of the specimen. 



Fiy. 5. Staicroplegma hrevispina, sp. n. The upper portion has been dis- 

 placed by a quartz-vein. 



Fiy. 6. StauropJegma cuinpressum, sp. n, 



Fiy. 7. Stnurodoras yracilis, sp. n. Only the base of the lower spine 

 remains. A quartz-vein traverses the specimen. 



Fiy. 8. Halio7nma cornidurn, sp. n. 



Fty. U. Triposphara Feachii, sp. n. 



Fiy. 10. Triposphcera densa, sp. n. 



Fig. 11. Triposphcera armata, sp. n. 



Fig. 12, Sphccrozoum patidu7n, s^. n. A geminate spicule, the rays im- 

 perfect, referred to this species. 



The figures have been drawn hy transmitted light from microscopic 

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

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

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

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

 text. 



