PLATE VI. 



Fia. Page. 



1. Uranaster ramseyensis (Hicks); photograph of oral surface, X 3. — 



Lower Ordovician (Arenig) ; Ramsey Island. Lightbody Collection, 



University Museum, Manchester, no. L. 1103G« . . 110 



2. Ditto; photograph of apical surface, X 3. — Ibid.; no. L. 11038 . 109 



3. Ditto; photograph of oral surface, X 3. — Ibid.; no. L. 11036^ . 110 



4. Ditto; photograph of apical surface, X 3. — Ibid.; no. L. 11037 . 109 



5. Lejpidactis wenlochi, n. sp.; X 1^; photograph of oral surface. — Middle 



Silurian (Wenlock) ; Dudley. British Museum (Nat. Hist.), no. 

 57426 ; M., madreporite . . . . .113 



6. Lepidaster grayi, Forbes, X 3 (approximately). — Ibid. Ketley Collec- 



tion, University of Birmingham, no. 221. . . .121 



