PLATE XVII. 



Fig. Page. 



1. Baliactu ordovicus, n. gen., n. sp. ; photograph of the oral surface. X -. 



-Upper Ordovician (Caradocian) ; Habberley Brook, Shropshire. 

 Shrewsbury Museum. 



2. Baliactis wenlockensis, n. sp. ; photograph of the oral surface, X oh. 



-Middle Silurian (Wenlock) ; Gutterford Burn, Pentland Hills. 

 Royal Scottish Museum, no. 32/439, 1897. 



3. Palasterina primsuva (Forbes) ; photograph of the oral surface of a group 



of individuals on the same slab, nat. size. — Upper Silurian (Ludlow) ; 

 Westmoreland. Kendal Museum. 223. 



4. Taeniactis wenloclci, n. sp. ; photograph of individual with arms Hexed 



upwards over the disc, x 4. — Middle Silurian (Wenlock) ; Gutter- 

 ford Burn, Pentland Hills. Royal Scottish Museum, no. 32/522, 1 897. 



5. Ditto; photograph of the oral surface, X 4. — Ibid. Royal Scottish 



Museum, no. 32/498, 1897. 



6. Pal&ura'?; photograph of the oral surface, x 1-2.— Ibid. Royal 



Scottish Museum, no. 32/ L69, 1897. 



