PLATE XVI. 



Pia. Pagb 



1. Palasterina antiqua (Hisinger) ; photograph of the apical surface, X 2. 



— Upper Silurian (Lower Ludlow) ; Leintwardine, Herefordshire. 



British Museum (Nat. Hist.), no. 40299. 228. 



'2. Ditto; photograph of the oral surface, the counterpart of the specimen 



photographed in fig. 1, X 2. _':>. 



3. Palasterina follw.anni, Start/, ; photograph of the oral surface, X §.— 



Lower Devonian ; Bundenbach, Germany. British .Museum (Nat. 

 Hist.), no. B. 13635. 235. 



4. Ditto ; photograph of the oral surface, X f. — Ibid. British Museum 



(Nat, Hist,), no. E. 13625. 235. 



5. Ditto; photograph of the oral surface, x f. — Ibid. British Museum 



(Nat, Hist.), no. E. 13636. 235. 



6. Ditto; photograph of the oral surface, X f. — [bid. British Museum 



(Nat. Hist.), no. E. 13629. 235. 



7. Ditto; photograph of the oral surface, X f. — Ibid. British Museum 



(Nat. Hist.), no. E. 13626. 235. 



8. Schuchertia stellata (Billings); photograph of the oral surface, x 4.— 



Middle Ordovician (Trenton); Ottawa, Canada. Geological Survey 

 of Canada, no. 1399. (Reproduced from Schuchert. op. cit., 

 pi. xxxii, fig. 2.) 211. 



