PLATE XVII. 



SILURIAN SPECIES. 



Fig. 



1. 1 a, 1 h. Pentamerus Knightii, Sow. Aymestry limestone, Aymestry. 



2. „ „ A very elongated example. Aymestry limestone, 



Mocktree, near Ludlow. 



3. „ „ In this specimen a portion of the dorsal valve has 



been removed, to show the V-shaped chamber of 

 the ventral valve. Aymestry limestone, N.E. 

 of Leintwardine. Miis. Geol. Survey. 



4. „ „ A very transverse specimen, from the Aymestry 



limestone, Aymestry. 



5. 5 a, 6. „ „ Two small specimens. Aymestry limestone, Mock- 



tree. 



7. 7 a. „ „ A young shell, found by Dr. Holl in the Wenlock 



limestone of Benthal Edge. 



8. „ „ A specimen seen from the beaks. (' Sil. Syst.,' 



pi. vi, fig. 8.) 



9. „ .„ Profile view of the interior of both valves. S, septum 



of ventral valve; V, dental plates; a, V-shaped 

 chamber; m and n, septa in dorsal valve; 0, 

 hinge-plate. 



10. „ „ Transverse section. The same letters refer to the 



same parts. 



11 — 14«. „ linguifer. Sow. Different ages and modifications in shape. 



Wenlock limestone, Dudley, and Rushall Canal, 

 Walsall. 



14 (5. „ „ Interior of both valves seen in profile. 



