PLATE XXVIII. 



Fig. 1. 



Figs. 2—4. 

 2. 



3. 

 4. 



Fig. 5. 

 Fig. 6. 



Figs. 7—13 

 7. 



8. 

 9. 



10. 



11. 

 12. 

 13. 



Fig. 14. 



MIDDLE SILURIAN (LLANDOVERY AND MAY HILL ROCKS). 



lUanus [Bimastus) MaccaUumi, Salter. Mullock, Girvan, Ayrshire. (Mus. 



P. Geol.) P. 210. 

 Illanus [Bysplams) TJiomsoni, Salter. P. 1 88. 



„ „ „ Internal cast, the same figured by Murchi- 



son, 'Quart. Geol. Journ.' From Mullock, 

 Girvan. (Mus. P. Geol., presented by 

 Sir Roderick I. Murchison.) 

 „ „ „ Tail of ditto. Same Locality and Museum. 



„ „ ,, Obscure young specimen. Purple shales 



(Tarannon shale) of Onny River, Shrop- 

 shire. (Mus. P. Geol.) 

 Illanus {B^/sjjIanus) amuhs, Salter. May Hill sandstone of Norbury. 



(Mus. P. Geol.) P. 187. 

 lUamis [Bysplaniis) Bowmanni, Salter. Same Locality and Museum as 



the last. P. 185. 



lower SILURIAN (CARADOC). 



Illanus [Bysplaniis) Bowmanni, Salter. P. 185. 

 „ „ „ Half-grown. Desertcreat, Tyrone. (Mus. 



P. Geol.) Portlock's original. 

 „ „ , Young. Same Locality and Museum. 



Young tail, very short. Shoals Hook, 

 near Haverfordwest. (Mus. P. Geol.) 

 „ „ Half-grown fine specimen from the Bala 



slates of Llanwddyn, Montgomeryshire. 

 (Woodwardian Museum ; M'Coy's figured 

 specimen of '//. centrotus!) 

 „ „ Variety, with longer and more connivent 



head-furrows. (Mus. P. Geol.) 

 „ „ Outline of large head. Shoals Hook, 



Pembrokeshire. (Mus. P. Geol.) 

 „ „ „ Young head. (Old Red ? conglomerates, 



derived from the) Coniston or Bala lime- 

 stone, Troutbeck. The species shows 

 the attachment of the lower(mandibular?) 

 muscles. (Mus. Wyatt-Edgell.) 

 lllanus [III.) Bailyi, Salter. Dunabrattin Head, Waterford. In lime- 

 stone. (Mus. Irish Survey.) P. 192. 



